Methods and Diets to Protect Against Chemotoxicity and Age Related Illnesses

ABSTRACT

A method of improving longevity and/or alleviating a symptom of aging or preventing age related diseases is provided. The method includes a step in which the subject&#39;s average and type of daily protein intake, IGF-I, and IGFBP1 levels, and risk factors for overall mortality, cancer and diabetes are determined. With respect to protein consumption, the relative amounts of protein calories from animal and plant sources are determined. A periodic normal calorie or low calorie but low protein fasting mimicking diet with frequencies of every 2 weeks to 2 months is provided to the subject if the subject&#39;s average daily protein intake level and type and/or IGF-I levels, and/or IGFBP1 levels is identified as being greater or lower than a predetermined cutoff intake/level and if the subject is younger than a predetermined age. The method is also shown to alleviate symptoms of chemotoxicity.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 14/178,953filed Feb. 12, 2014 which, in turn, claims the benefit of U.S.provisional application Ser. No. 61/763,797 filed Feb. 12, 2013, thedisclosures of which are incorporated in in their entireties byreference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention was made with Government support under Contract No. P01AG034906-01 awarded by the National Institutes of Health. The Governmenthas certain rights to the invention.

TECHNICAL FIELD

In at least one aspect, the present invention is related to method foralleviating symptoms of age-related illness and chemotoxicity.

BACKGROUND

Caloric restriction (CR) without malnutrition has been consistentlyshown to increase longevity in a number of animal models, includingyeast, C. elegans, and mice. However, the effect of CR on the lifespanof non-human primates remains controversial, and may be heavilyinfluenced by dietary composition. The lifespan extension associatedwith CR in model organisms is believed to operate through its effects onGH, GHR, leading to subsequent deficiencies in IGF-1 and insulin levelsand signaling. The effect of the insulin/IGF-1 pathway on longevity wasdiscovered in C. elegans, by showing that mutations in this pathway,regulated by nutrient availability, caused a two-fold increase inlifespan. Other studies revealed that mutations in orthologs of genesfunctioning in growth signaling pathways, including Tor-S6K andRas-cAMP-PKA, promoted aging in multiple model organisms, thus providingevidence for the conserved regulation of aging by pro-growth nutrientsignaling genes.

Recently, it has been shown that humans with growth hormone receptordeficiency (GHRD), exhibiting major deficiencies in serum IGF-1 andinsulin levels, displayed no cancer mortality, nor diabetes, and despitehaving a higher prevalence of obesity, combined deaths from cardiacdisease and stroke in this group were similar to those in theirrelatives. Similar protection from cancer was also reported in a studythat surveyed 230 GHRDs.

Protein restriction or restriction of particular amino acids, such asmethionine and tryptophan, may explain part of the effects of calorierestriction on longevity and disease risk, since protein restrictionreduces IGF-1 levels, can increase longevity in mammals independently ofcalorie intake, and has also been shown to reduce cancer incidence inrodent models.

Accordingly, there is a need for dietary interventions that canalleviate symptoms of age-related illness in both subjects willing tochronically modify their diet and those that would only considerperiodic interventions but otherwise continue their normal diet.

SUMMARY OF THE INVENTION

The present invention solves one or more problems of the prior art byproviding in at least one embodiment, a method of alleviating a symptomof aging or age related symptoms is provided. The method includes a stepin which the subject's average daily protein intake level is determined.In one refinement, the average daily protein intake level is expressedas the percent calories from protein that the subject consumes onaverage per day. With respect to protein consumption, the relativeamounts of protein calories from animal and plant sources aredetermined. A periodic low protein high nourishment diet in substitutionof their normal diet is provided to the subject if the subject's averagedaily protein intake level is identified as being greater than apredetermined cutoff protein intake level and if the subject is youngerthan a predetermined age.

In another aspect, a method for lowering glucose and/or IGF-1 levels ina subject is provided. The method includes a step of providing thesubject with a periodic low calorie and/or low protein diet having lessthan about 10 percent calories from plant based protein sources. Thesubject's glucose and/or IGF-1 levels are monitored to determine whetherprotein intake should be increased or decreased.

In another aspect, the low protein diet includes a supplement thatprovides excess levels of non-essential amino acids to be consumed for aperiod of 5 to 7 days together with very low protein amounts or noprotein diet. In a refinement, the low protein diet is alternated with anormal protein diet. In such variations, the low protein plant baseddiet is provided for 7 days every 2 weeks to 2 months with a normal dietof 1 to 7 weeks in between. Typically, the supplement provides one ormore of the following amino acids as a source of nitrogen: alanine,aspartic acid, cysteine, glutamic acid, glycine, histidine, proline,serine, and tyrosine while substantially excluding isoleucine, leucine,lysine, methionine, phenyalanine, threonine, tryptophan, valine, andarginine such that isoleucine, leucine, lysine, methionine,phenyalanine, threonine, tryptophan, valine, and arginine in combinationare present in an amount that is less than 5% of a total weight of thesubject's diet. In a further refinement, isoleucine, leucine, lysine,methionine, phenyalanine, threonine, tryptophan, valine, and arginine incombination are present in an amount that is less than 3% of a totalweight of the subject's diet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Table 9 showing the Calorie overview of the fasting mimickingdiet adjusted to human subjects. The fasting mimicking diet (FMD),Prolon, induces a fasting-like response while maximizing nourishment.The consumed calories for each one of the 5 days of the diet are shown,as well as the adjusted kcal per pound and kilogram of body weight. Thereduction in calories consumed during the 5 day dietary regimen (45-day)is shown as either 1) based on a 2,000 calorie per day diet, or 2) basedon 2,800, 2,400, and 2,000 calorie diets for person's weight ≧200,150-200, and ≦150 lbs, respectively;

FIG. 2. Table 10 showing the defined macronutrient content for each dietday adjusted to a 180-200 lbs human subject. The macronutrient contentfor each day of the 5 day FMD regimen based on an average 180-200 lbsperson. Caloric intake on day 1 of the diet is less reduced compared tothe following days (2-5) to allow the body to adjust to the low calorieconsumption. % of calories contributed by fat, carbohydrate (by sugar indetail) and protein for each day of the Prolon regimen is presented;

FIG. 3. Table 11 showing the defined micronutrient content for each dietday adjusted to a 180-200 lbs human subject in a variation of theinvention. The micronutrient content for each day of the 5 day FMDregimen based on an average 180-200 lbs person. Percent of the dailyvalue (% DV) is calculated based on a 2,000 calorie diet. * for some ofthe micronutrients, DV is not defined; values shown are based on thereference daily intake (RDI);

FIGS. 4A, 4B, 4C, 4D, and 4E. Using Cox Proportional Hazard Models,statistically significant (p<0.05) interactions between age and proteingroup were found for all-cause and cancer mortality. Based on thesemodels, predicted remaining life expectancy was calculated for eachprotein group by age at baseline. Based on results, low protein appearsto have a protective effect against all-cause and cancer mortality priorto age 66, at which point it becomes detrimental. No significantinteractions were found for cardiovascular disease (CVD) and diabetesmortality;

FIG. 5. Serum IGF-1 levels in respondents 50-65 and 66+ reporting low,moderate, or high protein intake. IGF-1 in respondents 50-65 issignificantly lower among those with low protein intake when compared tohigh (P=0.004). At age 66+ the difference between high and low intakebecomes marginally significant (P=0.101). The cohort for which IGF-1levels were calculated includes 2253 subjects. Of those ages 50-65(n=1,125), 89 were in the low protein category, 854 were in the moderateprotein category, and 182 were in the high protein category. Of thoseages 66+ (n=1,128), 80 were in the low protein category, 867 were in themoderate protein category, and 181 were in the high protein category.*P<0.01;

FIGS. 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H, 6I, 6J, 6K, 6L, 6M, 6N, 6O, and6P. (A) Tumor incidence in 18-week-old male C57BL/6 mice implanted with20,000 melanoma (B 16) cells, and fed either a high protein (n=10) orlow protein (n=10) diet. (B) B16 Tumor volume progression in (18 wk)C57BL/6 male mice fed either a high protein (n=10) or low protein (n=10)diet. (C) IGF-1 at day 16 in (18 wk) male C57BL/6 mice fed either a highprotein (n=5) or low protein (n=5) diet. (D) IGFBP-1 at day 16 in male(18 wk) C57BL/6 mice fed either a high protein (n=10) or low protein(n=10) diet. (E) B16 melanoma tumor progression in 10-month old femaleGHRKO mice (n=5) vs age-matched littermate controls (Ctrl; n=7). (F)Tumor incidence in 12-week-old female BALB/c mice implanted with 20,000cell breast cancer (4T1) fed either a high protein (n=10) or low protein(7%; n=10) diet. (G) 4T1 breast cancer progression in female (12 wk)BALB/c mice fed either a high protein (n=10) or low protein (n=10)diet.(H) IGF-1 at day 16 in female (12 wk) BALB/c mice fed either a highcasein protein (n=5) or low casein protein (n=5) diet. (I) IGFBP-1 atday 16 in female (12 wk) BALB/c mice fed either a high casein protein(n=10) or low casein protein (n=10) diet. (J) IGF-1 at day 16 in female(12 wk) BALB/c mice fed either a high soy protein (n=5) or low soyprotein (n=5) diet. (K) IGFBP-1 at day 16 in female (12 wk) BALB/c micefed either high soy protein (n=10) or low soy protein (n=10) diet. (L)Survival and (M) DNA mutation frequency of yeast exposed to a 0.5×, 1×,or 2× concentration of a standard amino acid mix. (N) PDS and STREactivity in yeast grown in media containing only Trp, Leu. and Hiscompared to those grown in the presence of all AA. (O) Ras2 deletionprotects against oxidative stress-induced genomic instability measuredas DNA mutation frequency (Can^(r)) in wild-type (DBY746) and ras2Δmutants chronically exposed to 1 mM H₂O₂, (P) A model for the effect ofamino acids on aging and genomic instability in S. cerevisiae. Aminoacids activate the Tor-Sch9 and Ras-cAMP-PKA pathway also activated byglucose and promote age- and oxidative stress-dependent genomicinstability in part via reduced activity of Gis1 and Msn2/4. *P<0.05,**P<0.01, ***P<0.001, ****P<0.0001;

FIGS. 7A and 7B. Effect of protein intake on body weight in young andold mice. (A) Young (18-week-old) (n=10) and old (24-month-old) (n=6)C57BL/6 mice fed a high (18%) protein diet. (B) Young (18-week-old)(n=10) and old (24-month-old) (n=6) C57BL/6 mice fed a low (4%) proteindiet;

FIG. 8. Table 12: Associations between Mortality and Protein intake;

FIGS. 9A, 9B, 9C, 9D, 9E, 9F, and 9G. (A) 30-day body weight of18-week-old male C57BL/6 mice fed isocaloric diets varying in proteincontent either high (18%) or low (4%). (B) 30-day food intake inkcal/day of 18-week-old male C57BL/6 mice fed isocaloric diets varyingin protein content either high (18%) or low (4%). (C) IGFBP-2 at day 16in male (18 wk) C57BL/6 mice fed either a high protein (n=10) or lowprotein (n=10) diet. (D) IGFBP-3 at day 16 in male (18 wk) C57BL/6 micefed either a high protein (n=10) or low protein (n=10) diet. (E) 30-daybody weight of 12-week-old female BALB/c mice fed isocaloric dietsvarying in protein content either high (18%) or low (7%). (F) 30-dayfood intake in kcal/day of 12-week-old female BALB/c mice fed isocaloricdiets varying in protein content either high (18%) or low (4%). (G)IGFBP-3 at day 16 in 12-week-old female BALB/c mice fed either a highprotein (n=10) or low protein (n=10) diet. *P<0.05, **P<0.01,***P<0.001, ****P<0.0001; ANOVA;

FIG. 10. Tumor volume progression of B16 melanoma in 10-month old femaleGHRKO mice (n=5) vs age-matched wild-type controls (Wt; n=13). **P<0.01;

FIGS. 11A, 11B, 11C, and 11D. (A) Yeast chronological survival and (B)attenuated age-dependent genomic instability shown as mutation frequencyin the CAN1 gene (measured as Can^(r) mutants/10⁶ cells) in wild-type(DBY746) compared to ras2Δ mutants. (C) Chronological survival ofwild-type and ras2Δ mutants chronically treated with 1 mM H₂O₂, (D) Lackof Ras2 protects against oxidative stress-induced genomic instability(mutation frequency Can^(r)). *P<0.05, **P<0.01, ****P<0.0001;

FIGS. 12A, 12B, 12C, 12D, 12E, and 12F. IGF-1 Moderates the Associationbetween Protein Consumption and Mortality. Based on results from CoxProportional Hazard Models of the interaction between protein and IGF-1on mortality, predicted Hazard Ratios were calculated by IGF-1 for bothmoderate and high protein groups relative to the low protein group. Nosignificant interactions between protein and IGF-1 were found forall-cause (3a) or CVD mortality (3b) in the 50-65 year old age group.However, the interaction for IGF-1 and high vs low protein wassignificant (p=0.026) for cancer mortality (3c) for subjects ages 50-65.Results show that for every 10 ng/ml increase in IGF-1 the mortalityrisk of cancer increases for the high protein group relative to the lowprotein group by 9% (HR_(high protein×IGF-1): 1.09; 95% CI: 1.01-1.17).The interaction between protein and IGF-1 was significant forrespondents ages 66+ only for CVD mortality. Those with high or moderateprotein diets had a reduced risk of CVD if IGF-1 was also low; however,as IGF-1 increased there was no benefit;

FIG. 13. Table 13: Sample Characteristics;

FIG. 14. Table 14: Association between Protein Intake and Mortality(N=6,381);

FIG. 15. Table 15: The Influence of IGF-I on the Association betweenMortality and Protein Intake (N=2,253);

FIG. 16. Table 16: Hazard Ratios for the Interaction between Protein andIGF-I on Mortality;

FIG. 17. Table 17: Influence of Animal and Vegetable Protein on theAssociations between Mortality and Protein intake;

FIG. 18. Table 18: Adjusted mean HbA1c, Diabetes Prevalence, and meanBMI by Age and Protein Intake;

FIG. 19. Table 19: Associations between Diabetes Mortality and Proteinintake, among participants with no diabetes at baseline;

FIGS. 20A, 20B, 20C, and 20D. Human subjects participated in 3 cycles ofa low protein low calorie and high nourishment 5-day fasting mimickingdiet (FMD, indicated in green, see text) followed by approximately 3weeks of normal diet (indicated in brown) (A). Blood were drawn beforeand at the end of the 5-day diet (time points A and B), and also 5-8days after finishing the 3^(rd) 5-day FMD (time point C). The 5-daydieting significantly reduced blood glucose (B), IGF-1 (c) and IGFBP-1(D) levels. Glucose *, p<0.05, N=18; IGF-1, **, p<0.01, *p<0.05, N=16;IGFBP-1, **, p<0.01, N=17; all statistical tests were performed aspaired t test, two tailed on the original values;

FIGS. 21A, 21B, 21C, 21D, 21E, and 21F. Calories supplied byMacronutrients of the Experimental Diets in %. AIN93G standard chow wasthe reference diet and supplied to all mice. The experimental dietsmodified in the macronutrient composition (fat, protein andcarbohydrates) were all based on this diet. The low-carbohydrate LCHPdiet had calories from carbohydrates reduced to 20% compared to theAIN93G formulation (13% vs. 63.9%) but contained more protein (45.2%)and fat (41.8%). Diets 20% P-1 (soybean oil as fat source) and 20% P-2(coconut oil as fat source) had calories from protein sources reduced to20% compared to the AIN93G formulation; the 0% P diet contained noprotein; all these diets were isocaloric to the AIN93G standard chow.The ketogenic high fat diet 60% HF was designed to supply 60% of theconsumed calories from fat sources, the calories coming from protein andcarbohydrates were reduced proportionally. The 90% HF diet was aketogenic diet which contains 90% of fat while supplying only minimalcarbohydrates (less than 1%) and half of the protein content (9%).Detailed diet composition and calorie content are summarized in Table14;

FIGS. 22A, 22B, 22C, and 22D. Calorie Restriction reduces Bodyweight,Glucose and IGF-1. A) Female CD-1 mice, age 12-15 weeks were either fedad lib (grey square) with AIN93G rodent standard chow, exposed to 40%,60%, 80% and 90% calorie restricted AIN93G diets (triangles) or fasted(STS, green rectangle) until mice lost 20% of their initial bodyweight(dotted line). N=5 per experimental group. All data presented asmean±SEM. B) Linear fit for the severity of the CR regimen vs. theduration (days) until 80% bodyweight was reached. C) Blood glucoselevels for mice once 80% bodyweight was reached. Red line representsmean; * p<0.05, *** p<0.001, ANOVA, Tukey's multiple comparison. D)Serum IGF-1 levels for mice once 80% bodyweight was reached. Red linerepresents mean; *** p<0.001, ANOVA, Tukey's multiple comparison;

FIGS. 23A, 23B, 23C, 23D, and 23E. Effects of Macronutrient definedDiets on Bodyweight, Food Intake, Glucose and serum IGF-1. Five femaleCD-1 mice, age 12-15 weeks were either fed ad lib with AIN93G rodentstandard chow (black circle) or with A) two different low protein diets(20% P-1 and 20% P-2), a diet low in carbohydrates but high in protein(LCHP), a protein deficient diet (0% P) or B) a high fat diet (60% HF)and ketogenic diet (90% HF). A detailed overview over the macronutrientsis given in Table. 1. C) Daily ad lib calorie intake for diets AIN93G,20% P-1, 20% P-2, LCHP and 0% P. D) Daily ad lib calorie intake fordiets 60% HF and 90% HF; AIN93G shown as reference. All data presentedas mean±SEM. E) Serum IGF-1 levels after 9 days of ad lib feeding. Linesrepresent mean; *p<0.05,*** p<0.001, ANOVA, Tukey's multiple comparisoncompared to AIN93G control;

FIGS. 24A and 24B. A) Stress Resistance Test for Calorie RestrictedMacronutrient defined Diets. Mice were fed ad lib (AIN93G), were fastedfor 60 h (STS) or fed with 50% calorie restricted diets with definedmacronutrient compositions (AIN93G, LCHP, 0% P, 60% HF, 90% HF) for 3days (green box) prior to an intravenous injection of doxorubicin (24mg/kg, red dashed line). Survival was followed for 25 days postinjection, after which the remaining animals were considered survivors.B) Blood glucose levels after 3 days of feeding ad lib and CR diets, aswell as after 60 h STS. Lines represent mean.* p<0.05, *** p<0.001,ANOVA, Tukey's multiple comparison. Survival data plotted frompair-matched pooled experiments with the statistical software Prism(GraphPad Software);

FIGS. 25A and 25B. Tumor Progression of GL26 Glioma and 4T1 BreastCancer in vivo. A) Subcutaneous tumor progression of murine GL26 gliomais shown by total tumor volume in mm³. Tumor measurements were startedonce the tumors became palpable under the skin at day 10. Animals werefed ad lib with either AIN93G (N=5) as a control or with the low proteindiet 20% P-1 (N=6). All data presented as mean±SEM. B) Subcutaneoustumor progression of murine 4T1 breast cancer is shown by total tumorvolume in mm³. Tumor measurements were started once the tumors becamepalpable under skin at day 12. Control animals (N=10) received notreatment and tumor progressed rapidly, reaching the endpoint volume of2000 mm³ by day 54 post tumor implantation. Cispaltin (CDDP) animals(N=9) were injected at days 15, 33 and 44. The first CDDP dose wasdelivered at 12 mg/kg by intra-venous injection, the two subsquentinjection were delivered at 8 mg/kg to avoid chemotoxicity. Mice in the50% ICR+ CDDP group (N=9) were fed in intermittent regimens with theAIN93G diet reduced to 50% of the daily calorie intake of the controlgroup for three days (ICR, green box) prior to cisplatin injection.Injection schedule inditical as for the CDDP group. All data presentedas mean±SEM; *** p<0.001, ANOVA, Tukey's multiple comparison, comparedto control;

FIGS. 26A and 26B. A) Food intake in kcal/day for animals fed ad lib(grey square) with AIN93G rodent standard chow, fed with 40%, 60%, 80%and 90% calorie restricted AIN93G diets (triangles) or fasted (STS,green rectangle) until mice lost 20% of their initial bodyweight. B)Blood glucose levels for mice after 48 h exposure to all experimentaldiets. Line represents mean; ** p<0.01, ***p<0.001, ANOVA, Tukey'smultiple comparison;

FIG. 27. Blood glucose levels after 9 days of ad lib feeding theindicated experimental diets. Lines represent mean;

FIGS. 28A and 28B. A) Bodyweight profile for mice that were fed ad lib(AIN93G) or fed with 50% calorie restricted diets with definedmacronutrient compositions (60% HF, LCHP, 0% P) for 3 days (green box)prior to an intravenous injection of doxorubicin (24 mg/kg, red dashedline). B) Bodyweight profile for mice that were fed ad lib (AIN93G), fedwith 50% calorie restricted diets with defined macronutrientcompositions (AIN93G, 90% HF) for 3 days or were fasted for 60 h (greenbox) prior to an intravenous injection of doxorubicin (24 mg/kg, reddashed line);

FIGS. 29A and 29B. Calories supplied by macronutrients of the classicketogenic diet and modified Atkins diet in %;

FIG. 30. Table 20. Overview about the Macronutrients and caloriescontained in the Experimental Diets;

FIG. 31. Table 21. Detailed Composition of Macronutrient Defined Diets;

FIG. 32. Table 22. Adjustment Schedule for Macronutrient Defined Diets;

FIG. 33. Table 23. Composition of Calorie Restricted Diets;

FIG. 34. Table 24. Composition of Calorie Restricted MacronutrientDefined Diets.

DETAILED DESCRIPTION

Reference will now be made in detail to presently preferredcompositions, embodiments and methods of the present invention. TheFigures are not necessarily to scale. The disclosed embodiments aremerely exemplary of the invention that may be embodied in various andalternative forms. Therefore, specific details disclosed herein are notto be interpreted as limiting, but merely as a representative basis forany aspect of the invention and/or as a representative basis forteaching one skilled in the art to variously employ the presentinvention.

Except in the examples, or where otherwise expressly indicated, allnumerical quantities in this description indicating amounts of materialor conditions of reaction and/or use are to be understood as modified bythe word “about” in describing the broadest scope of the invention.Practice within the numerical limits stated is generally preferred.Also, unless expressly stated to the contrary: percent, “parts of,” andratio values are by weight; the description of a group or class ofmaterials as suitable or preferred for a given purpose in connectionwith the invention implies that mixtures of any two or more of themembers of the group or class are equally suitable or preferred;description of constituents in chemical terms refers to the constituentsat the time of addition to any combination specified in the description,and does not necessarily preclude chemical interactions among theconstituents of a mixture once mixed; the first definition of an acronymor other abbreviation applies to all subsequent uses herein of the sameabbreviation and applies mutatis mutandis to normal grammaticalvariations of the initially defined abbreviation; and, unless expresslystated to the contrary, measurement of a property is determined by thesame technique as previously or later referenced for the same property.

This invention is not limited to the specific embodiments and methodsdescribed below, as specific components and/or conditions may, ofcourse, vary. Furthermore, the terminology used herein is used only forthe purpose of describing particular embodiments of the presentinvention and is not intended to be limiting in any way.

As used in the specification and the appended claims, the singular form“a,” “an,” and “the” comprise plural referents unless the contextclearly indicates otherwise. For example, reference to a component inthe singular is intended to comprise a plurality of components.

The term “essential amino acid” refers to amino acids that cannot besynthesized by an organism. In humans, essential amino acids includeisoleucine, leucine, lysine, methionine, phenylalanine, threonine,tryptophan, valine. In addition, the following amino acids are alsoessential in humans under certain conditions—histidine, tyrosine, andselenocysteine.

The terms “kilocalorie” (kcal) and “Calorie” refer to the food calorie.The term “calorie” refers to the so-called small calorie.

The term “subject” refers to a human or animal, including all mammalssuch as primates (particularly higher primates), sheep, dog, rodents(e.g., mouse or rat), guinea pig, goat, pig, cat, rabbit, and cow.

In an embodiment of the present invention, a method of alleviating asymptom of aging or age related symptoms is provided. For example, themethod of the present embodiment may prevent or treat diabetes orcancer, and delays age-related mortality and other age-related diseases.In other variations, the methods are useful for lowering glucose and/orIGF-1 levels in a subject. In still other variations, the methods areuseful for treating (e.g., alleviate a symptom of) chemotoxicity in asubject. Typically, the method alleviates one or more symptoms of theseconditions. In particular, a method of increasing longevity in a subjectis provided. In the present context, increasing longevity meansimproving a subjects chances of living longer. For example, when manysubjects having the same profile (weight, age, glucose levels, insulinlevel, etc. see below) as the subject are subjected to the methods ofthe invention, the average survival increases. The method includes astep in which the subject's average daily protein intake level isdetermined. In one refinement, the average daily protein intake level isexpressed as the percent calories from protein that the subject consumeson average per day. The subject's protein intake may be assessed by thesubject answer questions or filling out a written survey regarding thesubject's daily and weekly protein, fat, and carbohydrate consumption.With respect to protein consumption, the relative amounts of proteincalories from animal and plant sources are determined.

A low protein diet is provided to the subject if the subject's averagedaily protein intake level is identified as being greater than apredetermined cutoff protein intake level and if the subject is youngerthan a predetermined age. Typically, the predetermined age is from 60 to70 years. The predetermined age is, in order of increasing preference 60years, 61 years, 62 years, 63 years, 64 years, 66 years, 67 years, 68years, 69 years, 70 years, and 65 years, and younger.Characteristically, the low protein diet provides percent calories fromprotein that is less than the predetermined cutoff protein intake level.Typically, the predetermined cutoff protein intake level is 20% caloriesfrom proteins of the total calories consumed on average per day by thesubject. In a refinement, the predetermined cutoff protein intake levelis 15% calories from proteins of the total calories consumed on averageper day by the subject. In a refinement, the predetermined cutoffprotein intake level is 10% calories from proteins of the total caloriesconsumed on average per day by the subject. In another refinement, thepredetermined cutoff protein intake level is 5% calories from proteinsof the total calories consumed on average per day by the subject. Insome refinements, the low protein diet provides greater than, inincreasing order of preference, 40%, 50%, 60%, 70%, 80%, and 90%calories form protein that are plant sources such as soybeans.Advantageously, the low protein diet provides about 100% calories ofprotein from plant sources.

The subject's IGF-1 and/or IGFBP1 levels are monitored to determine thefrequency and type of diet the subject (e.g., see protein amounts below)should be on and specifically, whether the protein intake should beincreased or decreased (i.e., Typically, levels of IGF-I decrease andlevels of IGFBP1 increase after the subject is provided with one or morecycles of the low protein diet. In particular, the low protein dietlowers IGF-I by at least 10 percent and/or raises IGFBP1 levels by atleast 50% percent. In another refinement, the low protein diet lowersIGF-I by at least 20 percent and/or raises IGFBP1 levels by at least75%. In another refinement, the low protein diet lowers IGF-I by atleast 50 percent and/or raises IGFBP1 levels by at least 2 fold. If theIGF-I decreases and/or IGFBP1 increase is determined to be insufficient,the low protein diet can be adjusted to provide even low amounts ofcalories from protein sources.

In a variation of the present embodiment, a high protein diet isprovided to the subject if the subject's age is older than thepredetermined age providing a high protein diet to the subject, the highprotein diet having a protein calorie percentage that is greater thanthe predetermined cutoff protein intake level.

In another variation, the low protein diet is provided to the subjectfor a predetermined number of days. For example, the low protein diet isprovided to the subject for 2 to 10 days. In another refinement, the lowprotein diet is provided to the subject for 3 to 7 days. In manycircumstances, the low protein is periodically provided to the subject.The frequency with which the low protein diet is provided to the subjectis determined by the subject's levels of insulin resistance, fastingglucose levels, IGF-I, IGFBP1, obesity, Body Mass Index, weight loss inprevious 10 years, family history of cancer, family history of diabetes,family history of early mortality. The frequency can be as high as everymonth for subjects with high IGF-I levels (example above 200 ng/ml), lowlevels of IGFBP1 and/or insulin resistance to once every 3 months forsubjects with IGF-I between 120 and 200 ng/ml and no insulin resistance.

In a refinement, the low protein diet is a fasting mimicking diet thatprovides less than 10% of calories from proteins and/or with allproteins being plant-based as set forth in International Pat. Appl.PCT/US13/66236; the entire disclosure of this patent application ishereby incorporated by reference. In particular, the low protein diet isadministered for a first time period to the subject. As used herein,sometimes the low protein diet of this embodiment). In a refinement, thelow protein diet provides from 4.5 to 7 kilocalories per pound ofsubject for a first day (day 1) and then 3 to 5 kilocalories per poundof subject per day for a second to fifth day (days 2-5) of the lowprotein diet. A second diet is administered to the subject for a secondtime period. In a refinement, the second diet provides an overallcalorie consumption that is within 20 percent of a subject's normalcalorie consumption for 25 to 26 days (e.g., immediately) following thelow protein diet. Characteristically, it is observed that the level ofIGF-I decreases and the level of IGFBP1 increases. In a refinement, themethod of this embodiment is repeated from 1 to 5 times. In anotherrefinement, the method of this embodiment is repeated from 2 to 3 times.In still another refinement, the method of this embodiment is repeatedfor a period of years or throughout the subject's entire life with afrequency of every 1 to 3 months depending on the subjects IGF-I andIGFBP1 levels as well as protein intake The frequency can be as high asevery month for subjects with high protein intake (above 15% of caloriesfrom proteins) and/or high IGF-I levels (example above 200 ng/ml), andlow levels of IGFBP1 and/or insulin resistance to once every 3 monthsfor subjects with protein intake representing between 10-15% ofcalories, IGF-I levels between 120 and 200 ng/ml, and no insulinresistance.

In another refinement, the combination of the low protein diet and thesecond diet (e.g., the subject's normal diet and caloric intake) providethe subject with a total number of calories within 10 percent of thesubject's normal caloric intake. In another refinement, the combinationof the low protein diet and the second diet provides the subject with atotal number of calories within 5 percent of the subject's normalcaloric intake. In still another refinement, the combination of the lowprotein diet and the second diet provides the subject with a totalnumber of calories within 1 percent of the subject's normal caloricintake.

In a refinement, the fasting mimicking diet (FMD) involves completelysubstituting a subject's diet for 5 days. During this 5 day period,subjects consume plenty of water. For healthy subjects of normal weight(Body Mass Index or BMI between 18.5-25), the diet is consumed once amonth (5 days on the diet and 25-26 days on their normal diet) for thefirst 3 months and every 3 months thereafter (5 days every 3 months).The weight of the subject is measured and the subject must regain atleast 95% of the weight lost during the diet before the next cycle isbegun. Subjects with BMI of less than 18.5 should not undertake the FMDunless recommended and supervised by a physician. The same regimen (onceevery month for 3 months followed by once every 3 months thereafter) canbe adopted for the treatment, or in support of the treatment, of all ofthe conditions presented in the patent applications.

The consumption guidelines for the FMD include Nutrition Facts relativeto calories, macronutrients and micronutrients. Calories are consumedaccording to the user's body weight. Total calorie consumption is 4.5-7calorie per pound (or 10-16 calorie per kilogram) for day 1 and 3-5calorie per pound (or 7-11 calorie per kilogram) for day 2 to 5. FIGS.1-3 provides listings of the nutrients for day one through day five. Inaddition to the macronutrients, the diet should contain less than 30 gof sugar on day 1 and less than 20 g of sugar on days 2-5. The dietshould contain less than 28 g of proteins on day 1 and less than 18 g ofproteins on days 2-5, mostly or completely from plant based sources. Thediet should contain between 20 and 30 grams of monounsaturated fats onday 1 and 10-15 grams of monounsaturated fats on days 2-5. The dietshould contain between 6 and 10 grams of polyunsaturated fats on day 1and 3-5 grams of polyunsaturated fats on days 2-5. The diet shouldcontain less than 12 g of saturated fats on day 1 and less than 6 gramsof saturated fats on days 2-5. Typically, the fats on all days arederived from a combination of the following: Almonds, Macadamia Nuts,Pecans, Coconut, Coconut oil, Olive Oil and Flaxseed. In a refinement,the FMD diet includes over 50% of the recommended daily value of dietaryfiber on all days. In the further refinement, the amount of dietaryfiber is greater than 15 grams per day on all five days. The diet shouldcontain 12-25 grams of glycerol per day on days 2-5. In a refinement,glycerol is provided at 0.1 grams per pound body weight/day.

In a variation, the FMD includes the following micronutrients (at least95% non-animal based): over 5,000 IU of vitamin A per day (days 1-5);60-240 mg of vitamin C per day (days 1-5); 400-800 mg of Calcium per day(days 1-5); 7.2-14.4 mg of Iron per day (days 1-5); 200-400 mg ofMagnesium per day (days 1-5); 1-2 mg of copper per day (days 1-5); 1-2mg of Manganese per day (days 1-5); 3.5-7 mcg of Selenium per day (days1-5); 2-4 mg of Vitamin B1 per day (days 1-5); 2-4 mg of Vitamin B2 perday (days 1-5); 20-30 mg of Vitamin B3 per day (days 1-5); 1-1.5 mg ofVitamin B5 per day (days 1-5); 2-4 mg of Vitamin B6 per day (days 1-5);240-480 mcg of Vitamin B9 per day (days 1-5); 600-1000 IU of Vitamin Dper day (days 1-5); 14-30 mg of Vitamin E per day (days 1-5); over 80mcg of Vitamin K per day (days 1-5); 16-25 mcg Vitamin B12 are providedduring the entire 5-day period; 600 mg of Docosahexaenoic acid (DHA,algae-derived) are provided during the entire 5-day period. The FMD dietprovides high micronutrient content mostly (i.e., greater than 50percent by weight) from natural sources including: Kale, Cashews, YellowBell Pepper, Onion, Lemon Juice, Yeast, Turmeric. Mushroom, Carrot,Olive Oil, Beet Juice, Spinach, Tomato, Collard, Nettle, Thyme, Salt,Pepper, Vitamin B12 (Cyanocobalamin), Beets, Butternut Squash, Collard,Tomato, Oregano, Tomato Juice, Orange Juice, Celery, Romaine Lettuce,Spinach, Cumin, Orange Rind, Citric Acid, Nutmeg, Cloves, andcombinations thereof. Table 1 provides an example of additionalmicronutrient supplementation that can be provided in the FMD diet:

TABLE 1 Micronutrient Supplementation Supplement Formula Amount AmountRange Unit Vit A 1250 IU  900-1600 IU Vit C Ascorbic Acid C₆H₈O₆ 15.000010-20 mg Ca Calcium CaCO₃ 80.0000  60-100 mg Carbonate Fe FerrousFumarate C₄H₂FeO₄ 4.5000 3-6 mg Vit D3 Cholecalciferol C₂₇H₄₄O 0.00250.001-0.005 mg Vit E dl-Alpha C₂₉H₅₀O₂ 5.0000 3-7 mg Tocopheryl AcetateVit K Phytonadione 0.0200  0.1-0.04 mg Vit B1 Thiamine MononitrateC₁₂H₁₇N₅O₄S 0.3750 0.15-0.5  mg Vit B2 Riboflavin E101 C₁₇H₂₀N₄O₆ 0.42500.2-0.6 mg Vit B3 Niacinamide C₆H₆N₂O 5.0000 3-7 mg Vit B5 CalciumC₁₈H₃₂CaN₂O₁₀ 2.5000 1.5-4.0 mg Pantothenate Vit B6 PyridoxineC₈H₁₁NO₃•HCl 0.5000 0.3-0.7 mg Hydrochloride Vit B7 Biotin C₁₀H₁₆N₂O₃S0.0150 0.01-0.02 mg Vit B9 Folic Acid C₁₉H₁₉N₇O₆ 0.1000 0.07-0.14 mg VitCyanocobalamin C₆₃H₈₈CoN₁₄O₁₄P 0.0015 0.001-0.002 mg B12 Cr ChromiumCr(C6H4NO2)3 0.0174 0.014-0.022 mg Picolinate Cu Cupric Sulfate CuSO40.2500 0.18-0.32 mg I Potassium Iodide KI 0.0375  0.03-0.045 mg MgMagnesium MgO 26.0000 20-32 mg Oxide Mn Manganese MnSO₄ 0.5000 0.3-0.7mg Sulfate Mo Sodium Na₂MoO₄ 0.0188 0.014-0.023 mg Molybdate Se SodiumSelenate Na₂O₄Se 0.0175 0.014-0.023 mg Zn Zinc Oxide ZnO 3.7500 3-5 mg

In another embodiment, a diet package for implemented the diet protocolset forth above is provided. The diet package includes a first set ofrations for a low protein diet to be administered for a first timeperiod to a subject, the low protein diet providing from 4.5 to 7kilocalories per pound of subject for a first day and 3 to 5kilocalories per pound of subject per day for a second to fifth day ofthe low protein diet. The diet package includes rations that provideless than 30 g of sugar on the first day; less than 20 g of sugar on thesecond to fifth days; less than 28 g of proteins on the first day; lessthan 18 g of proteins on days the second to fifth days; 20 to 30 gramsof monounsaturated fats on the first day; 10 to15 grams ofmonounsaturated fats on the second to fifth days; between 6 and 10 gramsof polyunsaturated fats on the first day; 3 to 5 grams ofpolyunsaturated fats on the second to fifth days; less than 12 g ofsaturated fats on the first day; less than 6 grams of saturated fats onthe second to fifth days; and 12 to 25 grams of glycerol per day on thesecond to fifth days. In a refinement, the diet package further includessufficient rations to provide the micronutrients set forth above. In afurther refinement, the diet package provides instructions providingdetails of the methods set forth above.

In refinement of the embodiments set forth above, a 5-day supply of dietincludes: soups/broths, soft drinks, nut bars and supplements. The dietis administered as follows: 1) on the first day a 1000-1200 kcal dietwith high micronutrient nourishment is provided; 2) for the next 4 daysa daily diet of 650-800 kcal plus a drink containing a glucosesubstitution carbon source (glycerol or equivalent) providing between60-120 kcal are provided. The substitution carbon source does notinterfere with the effect of fasting on stem cell activation.

In another refinement of the embodiments set forth above, a 6-daylow-protein diet protocol includes: soups/broths, soft drinks, nut bars,and supplements. The diet is administered as follows: 1) on the firstday a 1000-1200 kcal diet plus with high micronutrient nourishment isprovided; 2) for the next 3 days a daily diet of less than 200 kcal plusa drink containing a glucose substitution carbon source providingbetween 60 and 120 kcal. This substitution carbon source, includingglycerol, does not interfere with the effect of fasting on stem cellactivation; 3) on the 5th day the subject consumes a normal diet; and 4)on day 6 an additional replenishment foods consisting of a high fatsource of 300 kcal and a micronutrient nourishment mix on day 6replenishment foods consisting of a high fat source of 300 kcal and amicronutrient nourishment mix are provided in addition to normal diet.

In still another refinement, a diet protocol includes: 6-day supply oflow-protein diet includes: soups/broths, soft drinks, nut bars, andsupplements. 1) on the first day a 1000-1200 kcal diet with highmicronutrient nourishment is provided; 2) for the next 3 days a dailydiet of 600 to 800 kcal which contains less than 10 grams of protein andless than 200 kcal from sugars; 3) on the 5th day the subject receives anormal diet; and 4) on day 6 an additional replenishment foodsconsisting of a high fat source of 300 kcal and a micronutrientnourishment mix on day 6 replenishment foods consisting of a high fatsource of 300 kcal and a micronutrient nourishment mix are provided inaddition to normal diet.

A particularly useful diet protocol and dietary packages are provided byWIPO Pub. No. WO2011/050302 and the dietary protocols herein. WIPO Pub.No. WO2011/050302 is hereby incorporated in its entirety by reference.In particular, subjects are provided with a low protein diet for a firsttime period, a second diet for a second time period, and an optionalthird diet for a third time period. The low protein diet provides thesubject with at most 50% of the subject's normal caloric intake with atleast 50% of the kilocalories being derived from fat, preferablymonounsaturated fats. The subject's normal caloric intake is the numberof kcal that the subject consumes to maintain his/her weight. Thesubject's normal caloric intake may be estimated by interviewing thesubject or by consideration of a subject's weight. As a rough guide,subject's normal caloric intake is on average 2600 kcal/day for men and1850 kcal/day for women. In certain instances, the low protein dietprovides the subject with from 700 to 1200 kcal/day. In a particularlyuseful refinement, the low protein diet provides the male subject ofaverage weight with about 1100 kcal/day and the female subject ofaverage weight with 900 kcal/day. Typically, the first predeterminedperiod of time is from about 1 to 5 days. In certain instances, thefirst predetermined period of time is 1 day. In order to put the levelof fat in the low protein diet in perspective, the U.S. Food and DrugAdministration recommends the following nutritional breakdown for atypical 2000 kilocalorie a day diet: 65 gram fat (about 585kilocalories), 50 grams protein (about 200 kilocalories), 300 gramstotal carbohydrates (about 1200 kilocalories). Therefore, in one versionof the low protein diet, a majority of the calories from carbohydratesand proteins are eliminated.

Although the low protein diet encompasses virtually any source of fat,sources high in unsaturated fat, including monounsaturated andpolyunsaturated fat sources, are particularly useful (e.g., omega-3/6essential fatty acids). Suitable examples of monounsaturated foodsources include, but are not limited to, peanut butter, olives, nuts(e.g., almonds, pecans, pistachios, cashews), avocado, seeds (e.g.,sesame), oils (e.g., olive, sesame, peanut, canola), etc. Suitableexamples of polyunsaturated food sources include, but are not limitedto, walnuts, seeds (e.g., pumpkin, sunflower), flaxseed, fish (e.g.,salmon, tuna, mackerel), oils (e.g., safflower, soybean, corn). The lowprotein diet also includes a component selected from the groupconsisting of vegetable extracts, minerals, omega-3/6 essential fattyacids, and combinations thereof. In one refinement, such a vegetableextract provides the equivalent of 5 recommended daily servings ofvegetables. Suitable sources for the vegetable extract include, but arenot limited to, bokchoy, kale, lettuce, asparagus, carrot, butternutsquash, alfalfa, green peas, tomato, cabbage, cauliflower, beets.Suitable sources for the omega-3/6 essential fatty acids include fishsuch as salmon, tuna, mackerel, bluefish, swordfish, and the like. In afurther refinement, the low protein diet incudes fat sources such thatat least 25 percent of calories from fat are short-chain fatty acidshaving from 2 to 7 carbon atoms and/or from medium-chain saturated fattyacids having from 8 to 12 carbon atoms. Specific examples of fatty acidsinclude lauric and/or myristic acid and fat sources include olive oil,kernel oil and/or coconut oil. In other refinement, wherein the lowprotein diet includes calories from fat in an amount from about 0 to 22percent of total calories contained in the diet.

In a refinement, the subject is then provided the second diet for asecond time period. The second diet provides the subject with at most900 kcal/day. In certain instances, the second diet provides the subjectwith at most 200 kcal/day. Typically, the second predetermined period oftime is from about 2 to 7 days. In certain particular instances, thesecond predetermined period of time is 3 days. In still anotherrefinement, the second diet includes a component selected from the groupconsisting of vegetable extracts, minerals, omega-3/6 essential fattyacids, and combinations thereof. In one refinement, such a vegetableextract provides the equivalent of 5 recommended daily servings ofvegetable. Suitable sources for the vegetable extract include, but arenot limited to, bokchoy, kale, lettuce, asparagus, carrot, butternutsquash, alfalfa, green peas, tomato, cabbage, cauliflower, beets.Suitable sources for the omega-3/6 essential fatty acids include fishoils from salmon, tuna, mackerel, bluefish, swordfish, and the like.

The effectiveness of the dietary protocols herein is monitored bymeasurement of a number of subject parameters. For example, it isdesirable that the subject's serum concentration of IGF-I be reduced by25-90% by the end of the second diet period, depending on the initialIGF-I and protein intake level and on the levels optimal for protectionagainst mortality described in the attached publications. It is alsodesirable that the blood glucose concentration in the subject be reducedby 25-75% by the end of the second diet period.

In another variation of the present embodiment, the low protein dietincludes amino acid specific supplement having certain amino acids.Typically, the supplement provides excess levels of non-essential aminoacids to be consumed for a period of 5 to 7 days together with very lowprotein amounts or no protein diet. In a refinement, the low proteindiet is alternated with a normal protein diet. In such variations, thelow protein diet is provided for 7 days every 2 weeks to 2 months with anormal diet of 1 to 7 weeks in between. In a refinement, the amino acidspecific supplement substantially excludes the following amino acidsisoleucine, leucine, lysine, methionine, phenyalanine, threonine,tryptophan, valine, and arginine. In this context, “substantiallyexcludes” means that the total of the excluded amino acids is less than,increasing order of preference, 5 weight percent, 3 weight percent, 1weight percent, and 0.5 weight percent of the total weight of thesubject's diet. Instead, the amino acid specific diet provides one ormore of the following amino acids as a source of nitrogen: alanine,aspartic acid, cysteine, glutamic acid, glycine, histidine, proline,serine, and tyrosine. Tables 2 to 4 provide characteristics of an aminoacid specific diet for a mouse which is also a protein restricted as setforth below. A typical mouse diet provides about 19 kcal per day. Forother mammals such as humans, the protein restricted (PR) diet is scaledto provide the requisite calories. For example, a typical caloric intakefor adults in the United States is about 2200 calories per day. Table 5provides the kilocalories per day from each source for human subjectswhile Table 6 provides the grams per day from each source for humans.

TABLE 2 Normal Diet PR diet Ingredients (g/kg) Corn Starch 397.49 397.49Maltodextrin 132 149.88 Sucrose 100 100 Soybean Oil 70 72 Cellulose 5050 Mineral 35 35 Vitamin 10 10 Choline 2.5 2.5 Bitartarate Tert- 0.01.01 butylhydroquinone Macronutrients (g/kg) Carbohydrate 601 617Nitrogen 177 183 Source Fat 72 72 Caloric density (kcal/g) 3.7600 3.7673

TABLE 3 Kilocalories in 1 kg of mouse from each food source. NORMAL DIETPR Carbohydrate 2404 2468 Nitrogen Source 708 732 Fat 648 648 calculated3760 3848

TABLE 4 Percent calories from each source (mouse). NORMAL DIET PRCarbohydrate 63.94 64.14 Nitrogen Source 18.83 19.02 Fat 17.23 16.84

TABLE 5 Calories per day from each source (Humans). NORMAL DIET PRCarbohydrate 1406.60 1411.02 Nitrogen Source 414.26 418.50 Fat 379.15370.48 Total (kcal) 2200.00 2200.00

TABLE 6 Grams per day from each source (Humans). NORMAL DIET PRCarbohydrate 351.65 352.75 Nitrogen Source 103.56 104.63 Fat 42.13 41.16Total (g) 497.34 498.54

In a refinement, a kilogram of the amino acid specific diet for a mouseincludes from about 2 g to 20 g alanine, 10 g to 30 g aspartic acid, 2 gto 20 g cysteine, 40 g to 80 g glutamic acid, 2 g to 20 g glycine, 2 gto 20 g histidine, 15 g to 50 g proline, 5 g to 30 g serine, and 5 to 30g tyrosine. For human subjects, these ranges are multiplied by a factor(i.e., about 0.572) to provide the composition of the dietaryformulation per day for human subjects. For example, the daily amountsof the specified amino acids for humans (2200 Calorie/day diet) in theamino acid specific diet are about 2 to 12 g alanine, 5 g to 30 gaspartic acid, 1 g to 7 g cysteine, 18 g to 73 g glutamic acid, 2 g to 9g glycine, 2 g to 10 g histidine, 9 g to 37 g proline, 5 g to 21 gserine, and 5 to 21 g tyrosine. In another refinement, the amino acidspecific diet includes from about 160 to about 240 g of the specifiedamino acids per kilogram of the diet. Therefore, for humans the aminoacid specific diet provides from about 80 to 160 g of the specifiedamino acids per day using a factor (0.572) to convert the per kilogramof diet value to a value representative of a human diet of about 2200Calories/day. In another variation, the amino acid specific dietincludes at least 6 amino acids selected from the group consisting ofalanine, aspartic acid, cysteine, glutamic acid, glycine, histidine,proline, serine, and tyrosine in the amounts set forth above. In stillanother variation, the amino acid specific diet provides the amounts ofamino acids in grams per Kg of human body weight per day set forth inTable 7. In particular, the amino acid specific diet provided thefollowing grams per Kg of human body weight per day 0.06 g alanine, 0.14g aspartic acid, 0.04 g cysteine, 0.45 g glutamic acid, 0.05 g glycine,0.06 g histidine, 0.23 g proline, 0.13 serine, and 0.13 g tyrosine. Inanother refinement, each of these amino acids is within a range of plusor minus 30 percent of the specified value.

TABLE 7 Human levels. Grams of each amino acid selected for the dementiaprotecting diet per Kg of human body weight per day. Formulationgrams/kg Body Weight AA NORMAL DIET PR Factor Ala 0.07 0.06 0.81 Asp0.13 0.14 1.09 Cys 0.02 0.04 2.05 Glu 0.20 0.45 2.23 Gly 0.06 0.05 0.94His 0.04 0.06 1.68 Pro 0.10 0.23 2.25 Ser 0.09 0.13 1.35 Tyr 0.06 0.132.19 Total 0.78 1.30

In another variation, the method includes a step of administering aprotein restricted (PR) diet to a subject for a first time period. In avariation, the low protein diet includes a dietary supplement ofspecific amino acids. In a refinement, the first time period is fromabout 5 days to 14 day with 7 days being typical. Moreover, the lowprotein diet provides the subject with from 70 to 100 percent of thesubject's normal caloric intake. The low protein diet includessubstantially only amino acids as a source of nitrogen. For example, theprotein restricted diet derives less than 10 percent of its caloriesfrom proteins. In another refinement, the protein restricted dietderives less than 5 percent of its calories from proteins. In anotherrefinement, the protein restricted diet derives zero percent of itscalories from proteins. In particular, the protein restricted dietsubstantially excludes the following amino acids isoleucine, leucine,lysine, methionine, phenyalanine, threonine, tryptophan, valine, andarginine. In this context, “substantially excludes” means that the totalof the excluded amino acids is less than, increasing order ofpreference, 5 weight percent, 3 weight percent, 1 weight percent, and0.5 weight percent. Instead, the protein restricted diet provides one ormore of the following amino acids as a source of nitrogen: alanine,aspartic acid, cysteine, glutamic acid, glycine, histidine, proline,serine, and tyrosine. Tables 2 to 4 provide characteristics a proteinrestricted diet including the dietary supplement for the mouse studiesthat are set forth below. A typical mouse diet provides about 19 kcalper day. For other mammals such as humans, the low protein diet isscaled to provide the requisite calories. For example, a typical caloricintake for adults in the United States is about 2200 kcalories per day.Table 5 provides the kilocalories per day from each source for humansubjects while Table 6 provides the grams per day from each source forhumans.

In a refinement, the amino acids in a kilogram of the low protein dietfor a mouse are provided in Table 8. In a refinement, a kilogram of thelow protein diet for a mouse includes from about 2 g to 20 g alanine, 10g to 30 g aspartic acid, 2 g to 20 g cysteine, 40 g to 80 g glutamicacid, 2 g to 20 g glycine, 2 g to 20 g histidine, 15 g to 50 g proline,5 g to 30 g serine, and 5 to 30 g tyrosine. For human subjects, theseranges are multiplied by a factor (i.e., about 0.572) to provide thedaily requirements for these amino acids per day for human subjects. Forexample, the daily amounts of the specified amino acids for humans (2200Calorie/day diet) in the low protein diet are about 2 to 12 g alanine, 5g to 30 g aspartic acid, 1 g to 7 g cysteine, 18 g to 73 g glutamicacid, 2 g to 9 g glycine, 2 g to 10 g histidine, 9 g to 37 g proline, 5g to 21 g serine, and 5 to 21 g tyrosine. In another refinement, theprotein restricted diet includes from about 160 to about 240 g of thespecified amino acids per kilogram of the diet. Therefore, for humansthe low protein diet provides from about 80 to 160 g of the specifiedamino acids per day using a factor (0.572) to convert the per kilogramof diet value to a value representative of a human diet of about 2200Calories/day. In another variation, the protein restricted diet includesat least 6 amino acids selected from the group consisting of alanine,aspartic acid, cysteine, glutamic acid, glycine, histidine, proline,serine, and tyrosine in the amounts set forth above. Table 8 provides anexample of the amino acid content in the protein restricted diet for amouse diet. Table 8 also provides a factor which is the ratio of aspecified amino acid in the protein restricted diet to that of thecontrol (normal diet). These ratios are equally applicable to othermammals such as human subjects. In still another variation, the lowprotein diet provides the amounts of amino acids in grams per Kg ofhuman body weight per day set forth in table 8. In particular, the PKdiet provided the following grams per Kg of human body weight per day0.06 g alanine, 0.14 g aspartic acid, 0.04 g cysteine, 0.45 g glutamicacid, 0.05 g glycine, 0.06 g histidine, 0.23 g proline, 0.13 serine, and0.13 g tyrosine. In another refinement, each of these amino acids iswithin a range of plus or minus 30 percent of the specified value.

In another variation, a method for lowering glucose and/or IGF-1 levelsin a subject is provided. The method includes a step of providing thesubject with a low protein diet having less than about 10 percentcalories from protein sources. The subject's glucose and/or IGF-1 levelsare monitored to determine whether protein intake should be increased ordecreased. In a refinement, the low protein diet has from 0 to 10percent calories from protein sources. In a further refinement, the lowprotein diet has from 0 to 5 percent calories from protein sources. Inanother refinement, the low protein diet typically has about 0 percentcalories from protein sources. In another refinement, the low proteindiet is also a low calorie diet which includes fat sources such that atleast 50 percent of calories from fat are from long-chain unsaturatedfatty acids as set forth above having from 13 to 28 carbon atoms.Typical fat sources include vegetable oil such as soybean oil. In afurther refinement, the low protein diet incudes fat sources such thatat least 25 percent of calories from fat are short-chain fatty acidshaving from 2 to 7 carbon atoms and/or from medium-chain saturated fattyacids having from 8 to 12 carbon atoms. Specific examples of fatty acidsinclude lauric and/or myristic acid and fat sources include olive oil,kernel oil and/or coconut oil. In other refinement, wherein the lowprotein diet includes calories from fat in an amount from about 0 to 22percent of total calories contained in the diet.

In another embodiment, a method for alleviating a symptom ofchemotoxicity in a subject is provided. The method includes a step ofproviding a low protein diet for a first time period, the low proteindiet including less than 10 percent calories from protein. A calorierestricted diet is provided to the subject for a second time period, thecalorie restricted diet having 0 to 50% of the calories of the lowprotein diet. In a refinement, the calorie restricted diet include from0 to 10% calories from protein sources. In a refinement, achemotherapeutic treatment is administered to the subject. Examples ofchemotherapeutic agents include, but are not limited to, doxorubicin,cyclophosphamide, cisplatin, 5-fluorouracil and combinations thereof.

The following examples illustrate the various embodiments of the presentinvention. Those skilled in the art will recognize many variations thatare within the spirit of the present invention and scope of the claims.

Low Protein Intake Experiments

An epidemiological study of 6,381 US men and women aged 50 and abovefrom NHANES were combined, the only nationally-representative dietarysurvey in the U.S., with mouse and cellular studies to understand thelink between the level and source of proteins and amino acids, aging,diseases, and mortality.

Results Human Population

The study population included 6,381 adults ages 50 and over from NHANESIII, a nationally representative, cross-sectional study. Our analyticsample had a mean age of 65 years and is representative of the U.S.population in ethnicity, education, and health characteristics (Table13).

On average, subjects consumed 1,823 calories, of which the majority camefrom carbohydrates (51%), followed by fat (33%), and protein (16%)—with11% from animal protein. The percent calories from protein was used tocategorize subjects into a high protein group (20% or more of caloriesfrom proteins), a moderate protein group (10-19% of calories fromproteins), and a low protein group (less than 10% of calories fromproteins).

Mortality follow-up was available for all NHANES participants throughlinkage with the National Death Index up until 2006 (22). This providedthe timing and cause of death. The follow up period for mortalitycovered 83,308 total person-years over 18 years, with 40% overallmortality, 19% cardiovascular disease (CVD) mortality, 10% cancermortality, and about 1% diabetes-caused mortality.

Association Between Protein and Mortality

Using Cox Proportional Hazard models we found that high and moderateprotein consumption were positively associated with diabetes-relatedmortality, but not associated with all-cause, CVD, or cancer mortalitywhen all the subjects above age 50 were considered. Results showed thatboth the moderate and high protein intake groups had higher risks ofdiabetes mortality, compared to participants in the low protein group.Although taken together these results indicate that moderate to highprotein intake promote diabetes mortality, larger studies are necessaryto test this possibility further. An alternative explanation for theelevated diabetes mortality in the higher protein group is thepossibility that, following a diabetes diagnosis, individuals may switchto a diet comprised of higher protein, lower fat, and low carbohydrateintake. To test this, we examined the association between protein intakeand diabetes mortality in participants who had no prevalence of diabetesat baseline (Table 19).

Among subjects with not diabetes at baseline those in the high proteingroup had a 73-fold increase in risk (HR: 73.52; 95% CI: 4.47-1209.7),while those in the moderate protein category had an almost 23-foldincrease in the risk of diabetes mortality (HR: 22.93; 95% CI:1.31-400.7). We underline that our hazard ratios and confidenceintervals may be inflated due to our sample size and the extremely lowincidence of diabetes mortality in the low protein group. Overall, therewere only 21 diabetes deaths among persons without diabetes atbaseline—only 1 of which were from the low protein group. Nevertheless,despite the small sample size, our results still show strong significantassociations between increased protein intake and diabetes-relatedmortality.

Cox Proportional Hazard models were rerun testing for an interactionbetween protein consumption and age, to determine whether theassociation between protein and mortality differed for middle-aged andolder adults. Significant interactions were found for both all-cause andcancer mortality, showing that low protein was beneficial in mid-life;however, its benefits declined with age (FIG. 4). Based on theseresults, we stratified the population into two age groups—those ages50-65 (n=3,039), and those ages 66+ (n=3,342) and reexaminedrelationships between protein and cause-specific mortality. Among thoseaged 50-65, higher protein levels were linked to significantly increasedrisks of all-cause and cancer mortality (Table 12). In this age range,subjects in the high protein group had a 74% increase in their relativerisk of all-cause mortality (HR: 1.74; 95% CI: 1.02-2.97), and were morethan 4-times as likely to die of cancer (HR: 4.33; 95% CI: 1.96-9.56)when compared to those in the low protein group. None of theseassociations were significantly affected by controlling for percentcalories from total fat or for percent calories from totalcarbohydrates. However, when the percent calories from animal proteinwas controlled for, the association between total protein and all-causeand cancer mortality was eliminated or significantly reduced,respectively, suggesting animal protein mediates a significant portionof these relationships. If we control for the effect of plant-basedprotein, there is no change in the association between protein intakeand mortality, indicating that high levels of animal proteins promotemortality and not that plant-based proteins have a protective effect(Table 17).

Compared to subjects with a low protein diet, subjects who consumedmoderate levels of protein also had a 3-fold higher cancer mortality(HR: 3.06; 95% CI: 1.49-6.25), that was not accounted for by eitherpercent calories from fat or percent calories from carbohydrates, butwas marginally reduced when controlling for percent calories from animalprotein (HR: 2.71; 95% CI: 1.24-5.91). Although the size of the effectwas not as large as for those in the high protein group. Taken together,these results indicate that respondents aged 50-65 consuming high levelsof animal protein display a major increase in the risks for overall andcancer mortality, however, the risks may be somewhat decreased ifprotein does not come from an animal source. Similar results wereobtained if the population 45-65 was considered (data not shown)

In contrast to the findings above, among respondents who were 66 yearsof age and over at baseline, higher protein levels were associated withthe opposite effect on overall and cancer mortality but a similar effecton diabetes mortality (Table 12). When compared to those with lowprotein consumption, subjects who consumed high amounts of protein had a28% reduction in all-cause mortality (HR: 0.72; 95% CI: 0.55-0.94),while subjects who consumed moderate amounts of protein displayed a 21%reduction in all-cause mortality (HR: 0.78; 95% CI: 0.62-0.99).Furthermore, this was not affected by percent calories from fat, fromcarbohydrates, or from animal protein. Subjects with high proteinconsumption also had a 60% reduction in cancer mortality (HR: 0.40; 95%CI: 0.23-0.71) compared to those with low protein diets, which was alsonot affected when controlling for other nutrient intake or proteinsource.

The Influence of IGF-1 on the Association Between Protein and Mortality

Adjusted mean IGF-1 levels were positively associated with proteinconsumption for both age groups (FIG. 5). Because IGF-1 was onlyavailable for a randomly selected subsample (n=2,253) we reexamined theage-specific associations between protein and cause-specific mortalityin this sample and found them to be similar to what was seen in the fullsample; although, with somewhat larger effect sizes (Table 15). Next weexamined whether IGF-1 acted as a moderator or mediator in theassociation between protein and mortality. We found that while IGF-1 didnot account for the association between protein consumption andmortality (Table 15), it was an important moderator of theassociation—as indicated by the statistically significant interactionsbetween protein and IGF-1 level (Table 16).

From these models, predicted hazard ratios by IGF-1 and protein groupwere calculated (FIG. 12). Results showed that for every 10 ng/mlincrease in IGF-1 the mortality risk of cancer among subjects ages 50-65increases for the high protein vs the low protein group by an additional9% (HR_(high protein×IGF-1): 1.09; 95% CI: 1.01-1.17). Alternatively,among older subjects (66+ years), when comparing those in the lowprotein group, subjects with high or moderate protein diets had areduced risk of CVD mortality if IGF-1 was also low; however, nobenefits were found as IGF-1 increases.

Protein Intake, IGF-1, and Cancer in Mice

To verify causation and further our study of mechanism, we studied theeffect of a range of protein intake (4-18%) similar to that of subjectsin the NHANES study, on the levels of circulating IGF-1, cancerincidence, and tumor progression in rodents. 18-week-old male C57BL/6mice were fed continuously for 39 days with experimental, isocaloricdiets designed to provide either a high (18%) or a low (7%) amount ofcalories derived from protein, without imposing CR or causingmalnutrition (FIGS. 9A,B).

To understand how the different levels of protein and IGF-1 levels mayaffect the ability of a newly formed tumor to survive and grow after oneweek on their respective diets, both groups were implantedsubcutaneously with 20,000 syngeneic, murine melanoma cells (B16). Tumormeasurements began 15 days post implantation at 22 days on theirrespective diets, at which point incidence was found to be 100% in thehigh protein level group but only 80% in the low protein level group(FIG. 6A). At day 25, incidence rose to 90% in the low protein group,and remained there until the end of the experiment (FIG. 6A). From day22 until the end of the experiment tumor size was significantly smallerin the group consuming lower amount of protein indicating a much slowertumor progression. At day 39 the mean tumor size was observed to be 78%larger in the high protein group (day 36 P=0.0001; day 39 P<0.0001)(FIG.6B). Blood samples were obtained and analyzed at day 16 to determine theeffect of protein intake on IGF-1 and the IGF-1 inhibitory protein,IGFBP-1. Serum IGF-1 was 35% lower (P=0.0004) in the low protein (4%)group when compared to animals fed the high protein (18%) diet (FIG.6C). Conversely, serum IGFBP-1 was 136% higher (P=0.003) in the lowprotein group compared to the high protein group (FIG. 6D).

To test further the hypothesis that the GHR-IGF-1 axis promotes cancerprogression, we implanted subcutaneous melanoma (B16) into GHR/IGF-1deficient GHRKO mice and their respective age- and sex-matchedlittermate controls (18-week-old male C57BL/6 mice). Tumor measurementsbegan 10 days post implantation and continued until day 18. The datashows that tumor progression is strongly inhibited in the GHRKO micewhen compared to progression in the control group (FIG. 6E; P<0.01).

We also used a breast cancer mouse model to test the relationshipbetween protein levels, tumor incidence, and progression. 12-week-oldfemale BALB/c mice were placed under the same dietary regimen asdescribed for C57BL/6 mice, except that the mice had to be switched froma 4% to a 7% kcal from protein diet within the first week in order toprevent weight loss (FIGS. 9E,F). After a week of feeding on these dietsmice were implanted subcutaneously with 20,000 cells of syngeneic,metastatic, murine breast cancer (4T1), and 15 days later were assessedfor tumors. On day 18 post-implantation (day 25 on the diet) tumorincidence was 100% in the high protein group but only 70% in the lowprotein group. The incidence in the low protein group rose to 80% at day39 where it remained until the end of the experiment (FIG. 6F). Tumorprogression data also shows that the groups on lower protein diets had asmaller mean tumor size. A 45% smaller mean tumor size was observed inthe low protein group compared to the high protein group by day 53 atthe end of the experiment (P=0.0038)(FIG. 6G). As for C57BL/6 mice,IGF-1 was measured at 16 days of dietary protein restriction. In the lowprotein intake group, IGF-1 levels were reduced by 30% compared to thosein the high level group (P<0.0001) (FIG. 6H). Additionally, a lowprotein intake also caused an IGFBP1 increase of 84% (P=0.001)(FIG. 6I),similar to what was observed in the C57BL/6 genetic background (FIG.6D). Similarly, when soy protein intake was reduced from high levels tolow levels we observed a 30% decrease in IGF-1 (p<0.0001) (FIG. 6J) anda 140% increase in IGFBP-1 (p<0.0001)(FIG. 6K). Although there was atrend for an effect of substituting the same level of animal proteinswith plant proteins on IGF-I and IGFBP1, the differences were notsignificant. These data suggest that lower protein intake may play arole in decreasing cancer incidence and/or progression in part bydecreasing IGF-1 and increasing the IGF-1 inhibitor IGFBP1. Additionalstudies on various types of animal vs plant based proteins are necessaryto determine their effect on IGF-I and IGFBP 1.

Cellular Studies

To understand whether there is a fundamental link between the level ofamino acids and lifespan, the impact of the presence of specificconcentrations of amino acids on yeast growth and development wasassessed by survival and mutation rate assays. A wild type DBY746 S.cerevisiae strain was grown in the presence of half (0.5×), standard(1×), and double (2×) amino acid concentration with all other nutrientsmaintained constant. Survival was measured at days 1, 3, 5, and 8. Nosurvival differences were observed during days 1 and 3. At day 5, the 2highest amino acid concentrations showed a trend for increasedmortality, which resulted in a 10-fold decrease in surviving cells byday 8 (FIG. 6L).

In order to assess the relationship between amino acids, aging, andage-dependent DNA damage we used aging S. cerevisiae to measurespontaneous mutation rate. The mutation rate was 3- and 4-fold higher in5 day old but not young cells exposed to 1× and 2× amino acid levels,respectively, compared to cells exposed to a 0.5× amino acidconcentration (FIG. 6M). These results indicate that even in unicellularorganisms, amino acids promote cellular aging and age-dependent genomicinstability.

To further discern the pathways involved in promoting age-dependentgenomic instability we measured the induction of stress responsive genesregulated by the Ras-PKA-Msn2-4 Tor-Sch9-Gis1 pathways in the presenceor absence of amino acids. For cells grown in control media containingonly Trp, Leu, and His (essential for growth in this strain) thepresence of all amino acids in the media reduced the induction of stressresistance genes, indicating that the addition of amino acids wassufficient to inhibit cellular protection (FIG. 6N).

The Tor-Sch9 pathway extends longevity but also promotes DNA mutations.To determine whether Ras-cAMP-PKA signaling also regulates age-dependentgenomic instability we studied ras2 deficient mutants. We confirmed thatras2Δ mutants are long-lived (FIG. 11A) but also show that inactivationof Ras signaling attenuated age- and oxidative stress-dependent genomicinstability (FIG. 11B, 11C, 6O, 11D).

Together, these results suggest a mechanism where amino acids are ableto affect mutation frequency and thus genomic instability, at least inpart, by activation of the Tor-Sch9 and Ras/PKA pathways and decreasedstress resistance (FIG. 6P).

Low Protein Intake and Weight Maintenance in Old Mice

Based on the observed opposite effects of a low protein diet in subjects50-65 year old versus those 65 and older and on the major drop in BMIand IGF-1 levels after age 65, we hypothesized that older subjects on alow protein diet may become malnourished and unable to absorb or processa sufficient level of amino acids. To test this possibility in mice, wefed young mice (18-week-old) and old mice (24-month-old) with isocaloricdiets containing either 18% or 4% animal protein. A very low proteindiet was purposely selected to reveal any sensitivity to proteinrestriction in an old organism. Whereas old mice maintained on a highprotein diet for 30 gained weight, old but not young mice on a lowprotein diet lost 10% of their weight by day 15 (FIGS. 4A,B) inagreement with the effect of aging on turning the beneficial effects ofprotein restriction on mortality into negative effects.

Discussion

Here, using a major nationally-representative study of nutrition in theUnited States population, our results show that among those ages 45 andabove, the level of protein intake is associated with increased risk ofdiabetes mortality, but not associated with differences in all-cause,cancer, or CVD mortality. Nevertheless, we found an age interaction forthe association between protein consumption and mortality, with subjectsages 50-65 years experiencing benefits from low protein intake andsubjects ages 66+ experiencing detriments from a low protein diet—atleast for overall mortality and cancer. This may explain why the strongassociation between protein intake, IGF-1, and mortality reported herehad not been previously described. Furthermore, among the 2253 subjectsfor whom IGF-1 levels were measured, the risks of all-cause and cancermortality for those with high protein intake compared to the low proteinintake group were increased even further for those who also had highlevels of IGF-1. This is in agreement with previous studies associatingIGF-1 levels to various types of cancer.

Notably, there was evidence that the type of protein consumed may beimportant. Our results showed that the proportion of proteins derivedfrom animal sources accounted for a significant proportion of theassociation between overall protein intake and all-cause and cancermortality. These results are in agreement with recent findings on theassociation between red meat consumption and death from all-cause, CVD,and cancer. Previous studies in the U.S. have found that alow-carbohydrate diet is associated with an increase in overallmortality and when such a diet is accompanied with increased consumptionof animal-based products, the risk of overall, as well as CVD and cancermortality, is increased even further . However, our study indicates thatthe effect of animal proteins on IGF-I, aging, diabetes and cancer maybe the major promoter of mortality for people age 45-65 in the 18 yearsfollowing the survey establishing protein intake. By then, the cohortthat was 65 at the time of the interview would be 83 years old,underlining that the high protein intake may promote mortality insubjects that are older than 65.

Our results from yeast and mice may also explain at least part of thefundamental connection between proteins, cancer and overall mortality byproviding a link between amino acids, stress resistance, DNA damage, andcancer incidence/progression. In mice, the changes caused by reducedprotein levels had an effect potent enough to prevent the establishmentof 10-30% of tumors, even when 20,000 tumor cells were already presentat a subcutaneous site. Furthermore, the progression of both melanomaand breast cancer was strongly inhibited by the low protein dietindicating that low protein diets may have applications in both cancerprevention and treatment.

Although protein intake is associated with increased mortality foradults who were middle-aged at baseline, there was also evidence that alow protein diet may be hazardous for older adults. Both high andmoderate protein intake in the elderly were associated with majorimprovements compared to the low group, suggesting that protein intakerepresenting at least 10% of the calories consumed may be necessaryafter age 65 or possibly 75 to reduce age-dependent weight loss and,possibly prevent an excessive loss of IGF-1 and of other importantfactors. Previous studies have noted that an increased protein intakeand the resulting increase in IGF-1 may prove beneficial in olderadults. In fact, the dramatic switch from the protective to thedetrimental effect of the low protein diet coincides with a time atwhich weight is known to stabilize and then decline. Based on previouslongitudinal studies, weight tends to increase up until age 50-60, atwhich point it becomes stable before beginning to decline steadily by anaverage of 0.5% per year for those over age 65. We speculate that thismay depend on the weight loss and frailty of subjects being consideredwith frail subjects who have lost a significant percentage of their bodyweight and have a low BMI being more susceptible to proteinmalnourishment. It is also possible that other factors such asinflammation or genetic factors may contribute to the sensitivity toprotein restriction in elderly subjects, in agreement with our mousestudies.

Although other studies have noted age-associated declines of nutrientabsorption in rodents related to changes in the pH microclimate,impaired adaptive response in the aged gut, and changes in themorphology of the intestine, there is still no clear association betweenmorphological and absorptive changes in ageing. In humans, some studieshave shown that dietary protein digestion and absorption kinetics arenot impaired in vivo in healthy, elderly men, however, these studieshave also reported increased splanchnic extraction of AAs which mightresult in decreased availability to peripheral tissues, and speculatethat in the case of low protein intake or increased protein requirementthe limited systemic availability of dietary AAs may contribute todecreased muscle protein synthesis. Furthermore, in humans other factorslike poor dentition, medication, and psychosocial issues also play asignificant role on rates of malnourishment.

IGF-1 has also been previously shown to decrease at older ages possiblyincreasing the risk of frailty, and mortality. Thus our findings mayexplain the controversy related to IGF-I and mortality indicating that aminimum levels of proteins and possibly IGF-1 is important in theelderly or that low circulating IGF-1 reflects a state of malnourishmentfrailty and/or morbidity. In fact, inflammation and other disorders areknown to decrease IGF-1 levels, raising the possibility that the lowprotein and low IGF-1 group may contain a significant number of bothmalnourished and frail individuals having or in the process ofdeveloping major diseases.

There are some limitations to our study which should be acknowledged.First, the use of a single 24-hour dietary recall followed by up to18-years of mortality assessment has the potential of misclassifyingdietary practice if the 24 hour period was not a normal day. However,93% of our sample reported that the 24 hour period represented a normalday. We also include this variable as a control in our analysis.Furthermore, the 24-hour dietary recall has been shown to be a veryvalid approach to identify the “usual diet” of subjects. While we mustadmit that the lack of longitudinal data on dietary consumption is apotential limitation of our study, study of dietary consistency over sixyears among older people revealed little change over time in dietaryhabits. Another study looking at dietary habits over twenty years showedthat while energy intake decreased for protein, fat, and carbohydratesas people aged, the decreases were equal across the three types.

Another limitation of our study is that classification of respondentsinto protein groups, and then stratifying the sample for analysis,produced relatively small sample sizes, especially for analysesinvolving diabetes mortality among persons without diabetes at baselineor participants in the IGF-lsubsample. As a result, our Hazard Ratiosand 95% confidence intervals may be much larger than what would havebeen seen with a larger sample size. Nevertheless, one would expect asmall sample size to decrease our power and make it harder to detectassociations. Therefore, our ability to detect significance indicatesthat the associations between protein and mortality are robust.Furthermore, the lower limits of the 95% confidence intervals from ourmortality analyses were well above 1.0, signifying that the increasedrisk is probably large. Finally, given these limitations, our study wasstrengthened by its use of reliable cause-specific mortality data, aswell as its inclusion of a large nationally-representative sample—afeature often missing from the previous literature.

Overall, our human and animal studies show that a low protein dietduring middle age may be useful for the prevention of cancer and overallmortality, through a process that may involve, at least in part,regulation of circulating IGF-1 and possibly insulin levels. Inagreement with other epidemiological and animal studies our findingssuggest that a diet, in which plant-based nutrients represent themajority of the food intake, is likely to maximize health benefits.However, we propose that up to age 65 and possibly 75, depending onhealth status, the 0.7 to 0.8 grams of proteins/kg of body weight/daypublished by the Food and Nutrition Board of the Institute of Medicine,currently viewed as a minimum requirement, may be protective versus the1-1.3 g grams of proteins/kg of body weight/day consumed by adults ages19-70. We also propose that at older ages, it may be important to avoidlow protein intake and gradually adopt a moderate to high proteinpossibly mostly plant based consumption to allow the maintenance of ahealthy weight and protection from frailty.

Experimental Procedures

Nutrient Intake for Human Data

Nutrient intake data is based on reports of food and beverage intakeduring a 24-hour period. Data were collected via an automated,microcomputer-based coding system, with information on over eightynutrients There are several advantages to using this method forcollecting dietary data. Given that the time elapsing betweenconsumption and recall is short, participants are typically able torecall more information. Also, unlike reporting methods, 24-hour dietaryrecall relies on data collection after consumption, reducing thepotential for assessment to alter dietary behaviors. Furthermore,24-hour recalls have been shown to be stronger estimates of total energyand protein consumption compared to the commonly used food frequencyquestionnaires and have also been shown to be a more valid measure oftotal energy and nutrient intake than both the Block food-frequencyquestionnaire, and the National Cancer Institute's Diet HistoryQuestionnaire. Finally, this approach has also been found to accuratelyassess energy, protein, fat, and carbohydrate intake, regardless of bodymass index.

Epidemiological Mortality Follow-Up

Mortality data were available from the National Death Index. Informationfor 113 potential underlying causes of death (UCOD-113) was used todetermine all-cause mortality, cardiovascular (CVD) mortality, cancermortality and diabetes mortality.

Statistical Analysis for Human Data

Cox Proportional Hazard Models were used to estimate the associationbetween intake of calories from protein on subsequent all-cause, CVD,Cancer, and Diabetes Mortality—with the latter three run using competingrisks structures. Next we tested the interaction between age and proteinconsumption on the association with mortality. Based on these results,we categorized subjects into two age groups (50-65 years and 66+ years),which were used in the remainder of the analyses. Age-StratifiedProportional Hazard Models were used to estimate the association ofpercent calories from protein with Mortality within the two age groups,and examine whether the relationship was influenced by percent ofcalories from fat, percent of calories from carbohydrates, or animalprotein. Hazard models were re-estimated for the IGF-1 subsample todetermine whether including IGF-1 changed the association betweenprotein intake and mortality. Finally, proportional hazard models wereused to examine the interaction between protein and IGF-1, and used tocalculate predicted hazard ratios for each protein group at variousIGF-1 levels, to determine whether protein intake differentially impactsmortality depending on levels of IGF-1. All analyses were run usingsample weights, accounting for sampling design, and controlling for age,race/ethnicity, education, sex, disease status, smoking, dietarychanges, and total calorie consumption.

Materials and Methods for Yeast and Mouse Experiments

Using Cox Proportional Hazard models we found no association betweenprotein consumption and either all-cause, CVD, or cancer mortality(Table 14). However, high and moderate protein consumption werepositively associated with diabetes-related mortality. One explanationis that diabetes may be more prevalent in these groups, possibly becauseof a switch to a higher protein, lower fat, and lower carbohydrateintake following a diabetes diagnosis.

Finally, high versus low protein consumption was found to be associatedwith an over ten-fold increase in the risk of diabetes mortality forsubjects age 66 and over. However, the much higher prevalence ofsubjects with a history of diabetes in the high protein group and thesmall number of subjects dying of diabetes in the low protein group mayaccount for this, thus emphasizing the need for additional studies todetermine the role of protein intake on diabetes incidence and mortality(HR: 10.64; 95% CI: 1.85-61.31).

Supplemental Materials and Methods

IGF-I in Human Data

Half of the subjects in NHANES III were randomly selected to take partin the morning examination, following a recommended nine hour fast. Ofthis sub-sample, 2,253 subjects included in our study complied and havemeasured fasting serum data for IGF-I. IGF-I was measured by DiagnosticSystems Laboratories Inc., using standard a laboratory protocol andreported in ng/ml.

Potential Confounders in Human Data

Age, race/ethnicity, education, sex, disease status, smoking, dietarychanges, and total calorie consumption were included in analyses aspotential confounders. Age was reported in years and top-coded at 90 inthe data set by NHANES to protect confidentiality of respondents. Dummyvariables were created to classify subjects into three race/ethnicitycategories: non-Hispanic whites, non-Hispanic blacks, and Hispanics,Education was indicated by years of schooling. Dummy variables werecreated for self-reported smoking status—never, former, and current.Subjects were also asked to report on their history of diseases, inquestions phrased as, “Has a Doctor ever told you had . . . ” and usedto create three dummy variables for presence of cancer, myocardialinfarction, and diabetes history. Recent changes in dietary intake wereassessed using responses to three questions—1) “During the past 12months, have you tried to lose weight?”; 2) “During the past 12 months,have you changed what you eat because of any medical reason or healthcondition?”; and 3) (Following the 24-hour dietary recall) “Compare foodconsumed yesterday to usual”. Waist circumference, which is preferred toBMI as an indicator of adiposity, was measured to the nearest 0.1 cmstarting on the right side of the body at the iliac crest.

Cancer models in Mice

All animal experiments were performed according to procedures approvedby USC's Institutional Animal Care and Use Committee. To establish asubcutaneous cancer mouse model, we injected 18-week-old, male C57BL/6mice as well as 10-month-old GHRKO mice, age-matched littermate controlmice, and wild type littermates with B16 melanoma cells, and12-week-old, female BALB/c with 4T1 breast cancer cells. Beforeinjection, cells in log phase of growth were harvested and suspended inserum-free, high glucose Dulbecco's modified Eagle's medium (DMEM) at2×10⁵ cells or 2×10⁶, and 100 ul (2×10⁴ cells per C57BL/6 or BALB/cmouse; 2×10⁵ cells per GHRKO mouse) was subsequently injectedsubcutaneously in the lower back. All mice were shaved beforesubcutaneous tumor injection. Tumor incidence was determined bypalpation of the injected area and tumor size was measured using adigital Vernier caliper starting 10-15 days post implantation. Theexperiments for C57BL/6 and BALB/c ended at different time points basedon USC IACUC approved humane endpoint criteria for tumor size andulceration. GHRKO (C57BL/6 background) mice were kindly provided by J.J. Kopchick (Ohio University, Athens).

Protein Restriction in Mice

AIN-93G standard chow was used as the casein-based high proteinreference diet (18% kcal from protein and low protein diet 1,O was usedas the casein-based low protein diet (4% kcal from protein) (HarlanLaboratories, WI). Diets were isocaloric and changes in kcal from fat orcarbohydrates occurred in proportion to changes in kcal from protein.Daily intake measurements began 1 week before commencing the experimentin order to establish a baseline intake amount. All animals were feddaily for the duration of the experiment, and were provided with chow inexcess of 50% of their baseline intake in order to allow ad lib,non-calorically restricted feeding. Before tumor implantation BALB/cmice were assigned to one of the 2 different kcal from protein groupsand were pre-fed for 1 week. Feeding of these mice was continuedthroughout the course of the experiment the same as described above. Todetermine the effect of low protein on old mice, 24-month-old C57BL/6mice were placed either in an 18% or 4% kcal from protein group and feda continuous diet as described above. Body weights and intake weredetermined daily. Animals had access to water at all times.

Serum mIGF-I and mIGFBP-1 Measurements in Mice

Mice were anesthetized with 3% inhalant isoflurane, warmed gently todilate the veins, and blood was collected from the tail vein to obtainserum weekly. Serum mIGF-I and mIGFBP-1 assays were performed aspreviously described (Hwang et al., 2008) using an in-house ELISA assayusing recombinant mouse IGF-I or IGFBP-1 protein and polyclonalantibodies from R&D systems (Minneapolis, Minn.).

Statistical Analysis for Mouse Data

IGF-I comparisons between groups were performed using Student's t test,IGFBP-1 group comparisons were performed by Student's t test and ANOVA,and tumor volume progression group comparisons were performed withtwo-way ANOVA using GraphPad Prism v.6. All statistical analyses weretwo-sided and P values<0.05 were considered significant.

Yeast Survival and Mutation Frequency Measurement

Cells of the widely used DBY746 yeast strain (MATα leu2-3,112 his3-Δ1trp1-289, ura3-52 GAL+) were made prototrophic by transformation withthe corresponding plasmid, inoculated onto 1 ml of complete syntheticmedium (SDC) and grown overnight at 30 degrees Celsius on an orbitalshaker at 200 RPM.

This starter culture was then split (1:100) onto fresh synthetic SDCmedia containing 0.5×, 1× or 2× of the standard amino-acid concentration(Hu et al., 2013) at a 5:1 flask volume to medium volume ratio and putback in the incubator at the very same conditions. Aliquots of eachculture were harvested every other day and proper dilutions plated ontorich YPD plates. Colony forming units (C.F.U.) were counted after twodays of growth. Percentage of survival was assessed considering the CFUat day 3 as 100% of survival. All experiments were made in triplicateand standard deviation is shown. For mutation frequency calculation, 10⁷cells were collected, at each survival time point, washed with water andplated onto synthetic complete (SDC) medium lacking arginine andsupplemented with 60 □liq-1 of canavanine (Can). Can resistant colonieswere measured after two to three days of growth at 30 degrees Celsiusand expressed as the number of Can resistant clones out of 10⁶ viableCFU.

Ras2 Experiment Growth Conditions

Yeast chronological life span was monitored in expired SDC medium bymeasuring colony-forming units (CFUs) every 48 h. The number of CFUs atday 1 was considered to be the initial survival (100%) and was used todetermine the age-dependent mortality.

Ras2 Experiment Can1 Mutation Frequency Measurements

Spontaneous mutation frequency was evaluated by measuring the frequencyof mutations of the CAN1 (YEL063) gene. In brief, overnight inoculationswere diluted in liquid SDC medium and incubated at 30° C. The cells'viability was measured every 2 d starting at day 1 by platingappropriate dilutions onto yeast extract peptone dextrose (YPD) mediumplates and counting the CFUs. To identify the canavanine-resistantmutants (Cad) in the liquid culture, an appropriate number of cells(starting amount of 2×10⁷ cells) was harvested by centrifugation, washedonce with sterile water, and plated on selective medium (SDC-Argsupplemented with 60 μg/ml 1-canavanine sulfate). Mutant colonies werecounted after 3-4 d. The mutation frequency was expressed as the ratioof Can^(r) to total viable cells.

Human Low Protein Intake Study

Human subjects participated in 3 cycles of a low protein low calorie andhigh nourishment 5-day fasting mimicking diet (FMD, indicated in green,see text) followed by approximately 3 weeks of normal diet (indicated inbrown) (a). Blood were drawn before and at the end of the 5-day diet(time points A and B), and also 5-8 days after finishing the 3^(rd)5-day FMD (time point C). The 5-day dieting significantly reduced bloodglucose (b), IGF-1 (c) and IGFBP-1 (d) levels. Glucose *, p<0.05, N=18;IGF-1, **, p<0.01, *p<0.05, N=16; IGFBP-1, **, p<0.01, N=17; allstatistical tests were performed as paired t test, two tailed on theoriginal values. The results of this study are found in FIG. 20.

Material and Methods for Chemotoxicity Experiments

2.1. Mice All animal protocols were approved by the Institutional AnimalCare and Use Committee (IACUC) of the University of Southern California.12-15 week old female CD-1, BalB/C or C57BL/6N mice (Charles River) weremaintained in a pathogen-free environment throughout the experiments.

2.2. Macronutrient Defined Diets AIN93G standard chow (Harlan) was usedas the reference diet and supplied to all mice if not indicatedotherwise. Diets modified in the macronutrient composition (fat, proteinand carbohydrates) were all based on AIN93G (FIG. 21 and Table 20).Diets 20% P-1 (soybean oil as fat source) and 20% P-2 (coconut oil asfat source) had calories from protein sources reduced to 20% compared tothe AIN93G formulation; the 0% P diet contained no protein; all thesediets were isocaloric to the AIN93G standard chow. The low-carbohydrateLCHP diet had calories from carbohydrates reduced to 20% compared to theAIN93G formulation (13% vs. 63.9%) but contained more protein (45.2%)and fat (41.8%). The ketogenic high fat diet 60% HF was designed tosupply 60% of the consumed calories from fat sources, the caloriescoming from protein and carbohydrates were reduced proportionally. The90% HF diet was a ketogenic diet which contains 90% of fat whilesupplying only minimal carbohydrates (less than 1%) and half of theprotein content (9%). Detailed diet composition and calorie content aresummarized in Table S2. Mice were fed with the AIN93G control dietbefore commencing the experiments and based on their initial bodyweightgrouped into the experimental groups (N=5/group). Mice were acclimatedto the test diets one week prior to the experiments (adjustment scheduleis shown in Table 22). All diets were supplied ad lib unless indicatedotherwise.

2.3. Calorie Restriction (CR) and Short-term Starvation (STS) Forcalorie restriction using the AIN93G diet, the standard chow wasgrounded into a powder and mixed in hydrogel (Clear H₂O) in thenecessary amounts to achieve 60%, 50%, 40%, 20%, 10% calorie density ofAIN93G (Table 23). The calorie restricted macronutrient modified dietswere prepared similarly (Table 24). To avoid malnutrition, all dietswere supplemented with vitamins, minerals, fiber and essential fattyacids matching those in AIN93G. Baseline food intake (3.7g or 14kcal/day) was determined with AIN93G feeding prior to the experiment(data not shown). For the short-term starvation (STS) regimen, mice hadno access to food for up to 60 hours.

For all CR and STS experiments, mice were single caged in standardshoebox-cages which were refreshed daily to avoid coprophragy or feedingon residual chow. Animals had access to water at all times and weresupplied with hydrogel to ensure sufficient hydration. Bodyweight ofeach individual animal was measured routinely during the CR or STSregimens.

2.4. Blood Collection for Glucose and IGF-1 Measurements Mice wereanesthetized with 2% inhalant isoflurane and blood was collected by leftventricular cardiac puncture. Blood was collected in tubes coated withK²-EDTA for serum preparation (BD). Blood glucose was measured with thePrecision Xtra blood glucose monitoring system (Abbott Laboratories).IGF-1 was measured using a mouse specific ELISA kit (R&D Systems).

2.5. Resistance to high-dose Chemotherapy 12-15 week-old female CD-1mice weighing 25-32g were starved for up to 60 h (STS) or fed with themacronutrient modified 50% CR diets for 3 days, followed by anintravenous injection of 24 mg/kg Doxorubicin (DXR, BedfordLaboratories). In all experiments mice were offered AIN93G standard chowafter chemo drug injection and monitored daily. Animals showing signs ofsevere stress and/or deteriorating health status were designated asmoribund and euthanized.

2.6. Subcutaneous Tumor Model Murine 4T1 breast cancer and GL26 gliomacells were maintained in DMEM (Invitrogen) supplemented with 10% fetalbovine serum (FBS) at 37° C. under 5% CO₂. Cells in log phase growthwere washed and suspended in PBS at 2×10⁶ cells/mL and injectedsubcutaneously (s.c., 2×10⁵ cells/mouse in 100 μL PBS) in the lower backregion of the mouse. Tumor size was measured using a caliper. To mimicmulti-cycle treatments in humans, mice were treated intravenously (i.v.,lateral tail vein) with Cisplatin (Teva Parenteral Medicines Inc.) threetimes on days 15, 33 and 44 after tumor inoculation at 12, 8 and 8 mg/kgbody weight, respectively. Mice were monitored daily and animals showingsigns of severe stress, deteriorating health status or excess tumor load(2000 mm³) were designated as moribund and euthanized.

2.7. Statistical Analysis Comparisons between groups in the glucose andIGF-1 measurements were done with ANOVA, followed by Tukey's multiplecomparison using GraphPad Prism v.5. All statistical analyses weretwo-sided and P values <0.05 were considered significant.

3. Results

3.1. Effects of Calorie Restriction on Glucose and IGF-1 Levels

Short-term starvation (STS) reduces serum levels of glucose and IGF-1,increases cellular protection against high-dose chemotherapy, andsensitizes malignant cells to chemotherapeutic drugs. STS effects onglucose and IGF-1 are usually achieved once animals lost approximately20% bodyweight. Thus, the 20% weight-loss was used as a criterion tocompare glucose and IGF-1 levels of calorie restricted diets to thoseobtained from a 60 h STS regimen.

The 20% weight-loss threshold was reached at 4 days for 90% CR, 6 daysfor 80% CR, 9 days for 60% CR, or 13 days for 40% CR (FIG. 22A and FIG.26A). The time to achieve 20% weight-loss strongly depends on theseverity of the calorie restriction (linear fit with r²=0.9976; FIG.22B). At 48 hours, the reduction in blood glucose levels correlates withthe severity of the calorie restriction (linear fit with r²=0.7931;Supplementary FIG. 26B). The 60 h fasting regimen (STS) reduces bloodglucose levels by 70% compared to that in ad lib fed mice (FIG. 22C,P<0.001). The 4 day 90% CR regime reduced blood glucose by approximately40%, significantly less than STS (P<0.05). In addition, a trend wasobserved for the effect of CR in lowering blood glucose depending on thelength of the CR-feeding: the glucose levels in the 13-day 40% CRfeeding was significantly (P<0.05) lower than in the 4-day long 90% CRgroup. However, no calorie restricted group resulted in blood glucoselevels that were lower than in the 60 h fasting group; and 9 or moredays of CR were required to obtain glucose lowering effects in the rangeof those in the fasted group (FIG. 22C). Mice of all experimental CRgroups, independently of the severity of the restriction, reachedsimilar serum IGF-1 levels once the 20% weight-loss margin was reachedand had significantly (P<0.001) lower IGF-1 levels than mice in the adlib control group (FIG. 22D).

3.2. Effect of Macronutrient Defined Diets on Glucose and IGF-1 Levels

A set of macronutrient-defined diets (FIG. 21 and Table 20) weredesigned based on the AIN93G rodent chow to determine whether therestriction of specific dietary constituents could mimic the effects ofSTS or short-term CR, on blood glucose and/or serum IGF-1. The lowprotein diets 20% P-1 (soybean oil as fat source) and 20% P-2 (coconutoil as fat source) have calories from protein sources reduced to 20%compared to the original AIN93G formulation while carbohydrates and fatare increased to maintain the diets isocaloric to AIN93G. The 0% P dietcontains no protein; carbohydrates as well as fat are increasedproportionally to keep the diet isocaloric to the standard chow. TheLCHP diet has the calories from carbohydrate sources reduced to 20%compared to the original AIN93G formulation (13% vs. 63.9%) but suppliesmore protein and fat. The high fat ketogenic diet 60% HF was designed tosupply 60% of the consumed calories from fat sources, the caloriescoming from protein and carbohydrates were reduced proportionally. The90% HF diet is a ketogenic diet that contains 90% of the calories fromfat while supplying only minimal (less than 1%) carbohydrates and has 9%of the calories from protein. Due to the higher fat proportions, theLCHP, 60% HF and 90% HF diets have a high caloric-density compared tothe AIN93G standard chow. Detailed diet composition and calorie contentare summarized in Table 21.

Female CD-1 mice were fed ad lib with the experimental diets for nineconsecutive days to establish bodyweight profiles (FIG. 23A, B) and tomonitor the caloric intake (FIG. 23C, D). A significant food aversionwas not observed but noticed that mice fed with the diet lackingproteins completely (0% P) reduced food consumption after 6 days (FIG.23C). The reduced calorie intake caused weight-loss for animals in thisexperimental group (FIG. 23A). Mice in the ketogenic high-fat groups(60% HF and 90% HF) consumed more calories during the 9 days of feedingthan mice fed with the AIN93G standard chow (FIG. 23D) and mice fed adlib with the ketogenic 90% HF diet rapidly gained weight after 4-5 days(FIG. 23B). CD-1 mice in the experimental groups fed with diets 20% Pand LCHP showed no difference in calorie intake or bodyweight comparedto the mice fed with the AIN93G control diet (FIG. 23A, C).

Blood glucose levels at day 2, day 5 and at day 9 from mice on themacronutrient modified diets were not different from those on thestandard chow diet (FIG. 27 and data not shown). By contrast, serumIGF-1 levels were significantly elevated (P<0.05) in mice on theketogenic 60% HF diet for 9 days but not for mice fed with the ketogenic90% HF diet (FIG. 23E). Interestingly, not only the macronutrientcomposition (e.g. the protein content) but also the fatty acid sourcedifferentially modulate circulating IGF-1 levels: the low protein diet20% P-1 (containing soybean oil as the only fat source) did not reduceIGF-1 levels but the low protein diet 20% P-2 (coconut oil as the onlyfat source) significantly (P<0.05) reduced IGF-1 levels and there are nodifferences in these diets other than the fat source. The mostnoticeable effect on serum IGF-1 was in mice fed the protein deficientdiet 0% P for 9 days. Circulating IGF-1 was reduced to approximately 30%of that in mice on the standard chow (FIG. 23E). The protein deficientdiet 0% P was the only diet that reduced serum IGF-1 levels comparableto the 60 h short-term starvation.

3.3. Short-Term Calorie Restriction and Fasting Improve StressResistance

In mice, reduced serum IGF-1 and blood glucose levels promote thecapability to cope with toxicity induced by high-dosed chemotherapeuticagents. Since short-term calorie restriction, but not the macronutrientdefined diets (except for complete protein removal), reduced IGF-1 andglucose levels, a combinatorial approach was used to test whether dietswith defined macronutrient deficiency fed at 50% of the regular dailycalorie intake could result in enhanced chemo toxicity protection. 20% Pdiets were not included in the stress resistance experiments due to thefact that diet 0% P showed much more pronounced effects on serum IGF-1.

Stress resistance was tested in CD-1 mice fed either ad lib with AIN93Gstandard chow or with macronutrient defined diets reduced to 50% of thenormal calorie intake for three days prior to doxorubicin (DXR, 24mg/kg, i.v.) treatment (FIG. 24A). In the 50% calorie restricted groupsmice lost 12-15% of their initial bodyweight after 3 days, whereas inthe STS group mice lost 20% of their weight after 60 h. Following DXRtreatment, AIN93G chow was provided ad lib for all animals and the miceregained weight until chemotoxicity-induced weight-loss set in (FIGS.28A, B). The weight-loss continued in all experimental groups until day8 post injection, after which many animals slowly recovered. Mice fedthe calorie restricted 0% P and LCHP diets never fully recovered theirinitial weight (FIG. 28A). Animals started to succumb to chemotoxicity9-18 days post injection (FIG. 24A), in agreement with the reportedonset and nadir days of myelo-suppression after DXR treatment(http://dailymed.nlm.nih.gov). Mice were considered survivors if theywere alive 25 days post DXR injection. Mice fed ad lib with the AIN93Gdiet 3 days prior to DXR injection showed the worst outcome with only16% surviving by day 25 (FIG. 24A). In contrast to the ad lib fed mice,the great majority (89%) of fasted (60 hours) mice survived thehigh-dose chemotherapy. Control mice treated with DXR showed signs oftoxicity including reduced mobility, ruffled hair and hunched backposture whereas mice in the STS group showed no visible signs of stressor pain after the treatment (data not shown). Three days feeding of thecombination of 50% CR with macronutrient modification prior to DXRinjection improved the stress resistance in mice and resulted in 45-55%survival (FIG. 24A). There was no indication that fat or carbohydratecontent affected the results because all diets achieved a similar rateof protection. The data indicates that short-term CR, not the fat orcarbohydrate composition of the diet, confers partial chemo-protectionwhich are not as potent as to those caused by fasting. Mice fed the 50%CR LCHP diet performed worse than all other CR fed groups, presumablybecause of the effect of the high protein content of this diet on IGF-1.

Blood glucose measurements revealed that three-days feeding of thecalorie restricted modified diets was not sufficient to significantlyreduce glucose levels, with the exception of the 50% CR ketogenic 90% HFdiet (FIG. 24B). The reduction in glucose levels in the ketogenic groupdid not appear to enhance stress resistance. Mice in the STS group hadsignificantly lower blood glucose levels than all other experimentalgroups (FIG. 24B).

3.4. A Low Protein Diet Does Not Appear Delay GL26 Glioma Progression

Diets low in protein have been shown to lower cancer risks whilehigh-calorie and high-protein diets are linked to obesity and promotehormonal, metabolic, and inflammatory alterations that modulatecarcinogenesis. To test the effects of a low protein diet in a gliomamodel, mice were switched from the standard chow (18.8% of calories arefrom protein, Table 1) to a diet low in protein (20% P-1, 3.9% ofcalories are from protein) 10 days after the implantation of GL26 cellswhen the tumor was palpable (FIG. 25A). Low protein diet fed micedisplayed tumor progression that was not distinguishable from that inmice fed ad lib with the AIN93G diet (FIG. 25A). These results indicatethat the tumor progression could not be retarded by protein-restrictiononce the tumor was established.

3.5. Short-Term Intermittent Calorie Restriction Does Not EnhanceEfficacy of Chemotherapy Against Breast Cancer

The efficacy of STS in augmenting the treatment of various cancers istwofold: it protects against chemotherapy-induced toxicity to normalcells/tissues and sensitizes malignant cells to chemotherapeutic agents.Nonetheless, even short interval fasting (e.g. 4 days) can be achallenge for the majority of people and thus the “milder” calorierestricted approach could be a more feasible solution. To test whether ashort-term intermittent 50% CR (ICR) diet could result in similarbeneficial effects as the established fasting protocols, murine 4T1breast cancer cells were implanted subcutaneously into female BalB/Cmice and monitored the tumor progression. Twelve days after tumorimplantation, the tumor volume was measured and mice were assigned toeither the untreated control group (AIN93G), a group treated withcisplatin (CDDP) or a group intermittingly fed with 50% CR (ICR) forthree days prior to cisplatin treatment. The tumor in the untreatedcontrol group progressed rapidly and reached the experimental endpointvolume of 2000 mm³ 54 days after tumor implantation (FIG. 25B, blackcircles). Three cycles of cisplatin treatment delayed the tumorprogression; the tumor volume of these mice was approximately half thesize of that in untreated mice (FIG. 25B, blue squares). In contrast toSTS, an intermittent 50% calorie restricted AIN93G feeding regimen fedto mice for three days prior to the cisplatin injections did not resultin the sensitization of the tumor and did not augment the chemotherapy(FIG. 25B, orange triangle). Tumor volumes in this experimental groupdid not significantly differ from tumor volumes in mice that weretreated with cisplatin alone.

4. Discussion

It has previously been shown that a major reduction in blood glucose andIGF-1 levels is partly responsible for the beneficial effects of 2-3days of fasting in animal cancer models. In mice, a 60 h short-termfasting reduces bodyweight by 20% or more, serum IGF-1 by up to 75%, andglucose by up to 70%. Under these conditions, animals become highlystress resistant, in agreement with results in yeast, and a variety oftumors are sensitized to chemo-and radio-therapy. When a 20% weight-losswas employed as an endpoint, as expected, various degrees of CR regimensresulted in progressively quicker weight loss but also reduction inIGF-1 and glucose. However, it was also observed that the much shorterSTS regimen had more pronounced effects on glucose than most of the CRdiets, even when the CR diets were maintained for 9-13 days and causedan equivalent 20% weight loss. The less pronounced effects of calorierestricted diets, when compared to short-term starvation, might beexplained by a distinct physiological response that is unique toconditions under which nutrients are completely absent (Lee and Longo,2011). For example, the decrease in blood glucose caused by short-termfasting in this study was 70% and occurred within 60 h vs. the 40%glucose reduction caused by a 90% CR diet after 96h.

When deprived of food, mammals generally undergo three metabolicstages: 1) a post-absorptive phase, lasting for 10 or more hoursfollowing food ingestion, which involves the use of glycogen as the mainstored energy source, 2) an amino acid-dependent glucose generation bygluconeogenesis once the liver glycogen storage has been depleted, and3) a phase in which the remaining glucose is mostly consumed by thebrain while glycerol and fatty acids are released from adipose tissueand become the major energy source. The fat-derived ketonebodies becomethe main carbon sources in a matter of days of fasting. Within the body,these changes trigger a cellular response including the down-regulationof pathways involved in proliferation, cell growth and the reducedproduction of reactive oxygen species while simultaneously increasinggenomic stability and cellular stress resistance. Glucose is the majorenergy source for proliferating cells such as malignant cells andelevated blood glucose has been associated with increased cancer risk.Many cancer cells have elevated glucose uptake rates and rely onglycolysis followed by lactic acid fermentation even in the presence ofoxygen, instead of glycolysis followed by oxidation of pyruvate, aphenomenon known as the Warburg effect (Oudard et al., 1997; Warburg,1956). In normal cells, the reduction of blood glucose as well as IGF-1likely contribute to a differential regulation of the activation ofstress resistance transcription factors that are negatively regulated bynutrient sensing pathways and cell cycle progression. In cancer cells,the low glucose instead presents a specific and major challenge;particularly when chemotherapy drugs are also present.

In agreement with the partial effects on blood glucose and IGF-1, theresults of this disclosure indicate that 72 hour of 50% CR, but also ofdiets restricted in carbohydrates or proteins, have only partial effectson stress resistance. The combination of a short-term intermittent 50%CR regimen and cisplatin treatment did not appear in the augmentation ofchemotherapy efficacy in contrast to the combination of STS andchemotherapy. The present disclosure suggests that three days of a 50%ICR did not significantly reduce blood glucose levels and thus might notcause a sufficient reduction in the carbon sources metabolized by murinebreast cancer cells within this interval. None of the 50% dietaryrestricted and macronutrient defined diets fed for 3 days, except forthe ketogenic 90% HF diet, lowered blood glucose levels, which has beenshown to promote host-protection and tumor sensitization. Interestingly,a 50% reduction in the calories consumed on a ketogenic diet leads to a30% reduction in blood glucose levels after three days of feeding, aneffect presumably due to the very low carbohydrate content (less than1%) of this diet. However, stress resistance experiments in thisdisclosure indicate that this reduction did not improve survival. Inaddition, no mice from any of the CR diets achieved protectionequivalent to that caused by 60 h fasting (STS) in the experimentspresented here. Additional studies with extended feeding regimes andlarger experimental group size will be necessary to understand whetherspecific diets may be sufficient to achieve DSR and DSS effects that areclose to those caused by fasting cycles. Future studies could alsoevaluate the effects of various macronutrient-defined and CR diets onROS production, tumor progression and stress resistance.

Dietary protein and resulting amino acid-content seems to affectlongevity and healthy aging. Restricting protein intake shares some ofthe physiological effects of CR, including a decreased metabolic rate,reduced oxidative damage, enhanced hepatic resistance to toxins andoncogenic insults, decreased preneoplastic lesions and tumors.Furthermore, both CR and protein restriction reduce serum IGF-1 levels,which might be one of the contributors to longevity extension as theIGF-1-like signaling pathways regulate lifespan in various modelorganisms such as C. elegans, D. melanogaster and mice. The IGF-1pathway has been shown to affect both animal life span and sensitivityto oxidative stress, consistently with the greater resistance tooxidative stress in IGF-1 receptor deficient mice. The forkhead boxprotein O1 (FOXO1), a down-stream target of IGF-1/AKT signaling, canenter the nucleus in the absence/reduction of IGF-1/AKT signaling whereit can modulate a wide array of genes involved in oxidative stressresistance, longevity, and metabolism, and thus it is a key mechanisminvolved in protection against age associated stress and diseasedevelopment. It has previously been suggested that a reduction in IGF-1results in improved stress resistance to high dose chemotherapy as wellas tumor sensitization. IGF-I exerts a potent tumorigenic effect on avariety of cancer cells by increasing their proliferative rate andinhibiting apoptosis. Studies in mice with deficiencies in thedownstream effectors of IGF-R signaling, including mTOR inhibition byrapamycin and S6K1, demonstrate the central role of intracellularmitogenic pathways downstream of IGF-I in regulating lifespan and stressresistance while simultaneously reducing tumor growth. In addition,humans with growth hormone receptor deficiency have significantly lowercirculating IGF-1 levels, and also exhibit drastically reduced incidenceof cancer and diabetes, which are more common among age matchedrelatives with intact growth hormone receptor.

Mice in the group fed with a calorie restricted low carbohydrate diet(LCHP) had the worst survival of all CR groups, comparable to that ofmice in the control group. The fact that mice in this group consumedsimilar, or higher amounts of fat-derived calories (20.9% in 50% CR LCHPvs. 17.2% ad lib AIN93G) and more importantly protein-derived calories(22.6% in 50% CR LCHP vs. 18.8% ad lib AIN93G) during three days offeeding, might explain this lack of protection. Of note is that theresults presented on the induction of stress resistance are based onrelatively short (72h) feeding periods, thus if cannot be excluded thatlonger CR regimen with either altered calorie and/or macronutrientrestrictions could result in an improved stress resistance.

Ketogenic diets are used extensively in the treatment of refractoryepilepsy in children, but have also been studied in cancer treatment. Todetermine how this approach would compare with our stress resistance andpotentially tumor sensitization experiments, two ketogenic diets weredesigned: our 90% HF diet (% calorie ratio of fat: carbohydrates:protein of 90%: 1%: 9%; FIG. 21) is nearly identical (±0.5% variation)to the classic ketogenic diet with a ratio of fat: carbohydrates:protein of 90%: 1.4%: 8.6% respectively (FIG. 29). The high-fat diet 60%HF (% calorie ratio of fat: carbohydrates: protein of 60%: 31%: 9%)contains fat ratios similar to the fat ratio used in the modified Atkinsdiet (% calorie ratio of fat: carbohydrates: protein of 60%: 5%: 35%;FIG. 29), but the protein content was reduced because previous work hasestablished that protein, and not carbohydrates, regulate IGF-1 levelsin human. The results described here demonstrate that neither glucosenor IGF-1 levels were significantly reduced after feeding both ketogenicdiets for 9 consecutive days.

To evaluate the effects of saturated vs. unsaturated fatty acids, aswell as medium- vs. long-chain fatty acids in cancer treatment, twodiets were designed that were isocaloric to the control diet withsoybean oil or coconut oil as a fat source but had low protein content.Long-chain unsaturated fatty acids are found in most commonly useddietary fats and vegetable oils such as soybean oil, while short-andmedium-chain saturated fatty acids (e.g. lauric acid and myristic acid)are found in relatively high abundance in palm kernel oil and coconutoil. The medium-chain triglycerides (MCT) can easily by hydrolyzed inthe gastro-intestinal tract and can be transported through the portalvenous system towards the hepatocytes, while most of the long-chainfatty acids are transported as chylomicrons in the lymphatic system andpackaged into triglycerides in the liver. MCTs can easily be fed intothe mitochondrial β-oxidation, while LCTs rely on transporters, such ascarnitine, to enter the mitochondrial matrix in hepatocytes. Data fromhuman studies has indicated that consumption of MCTs or diets withhigher unsaturated to saturated fatty acid ratio are associated withdecreasing blood glucose, improving lipid profile, and reducing obesity.In a study of biochemical and anthropometric profiles in women withabdominal obesity, dietary supplementation with coconut oil promoted areduction in abdominal obesity.

The beneficial effects of prolonged CR are known for over a century now.The problems associated with translating CR into any clinicalapplication is that long-term CR delays but does not stop theprogression of many malignant diseases and is associated with a chronicreduced weight state that might be detrimental for cachectic cancerpatients, or patients at risk to become cachectic, but also mightchronically reduce fat and other reserves that may increase frailtyparticularly in elderly patients. In fact, prolonged CR can delay woundhealing and immune function, which might present an additional hurdlefor the great majority of patients receiving chemotherapy or undergoingsurgery. Furthermore, the 75% reduction in serum IGF-1 caused by a2-5-day fast in mice and humans cannot be achieved by a more moderate CRwhich does not reduce IGF-1 levels in humans unless the protein intakeis also restricted. Even when combined with protein restriction, chronicCR only causes a 30% reduction of IGF-1 in humans. Because of theconsistent effects on glucose and IGF-1, and consequent effects onprotection of normal and sensitization of cancer cells without thechronic under-weight, periodic fasting cycles appear to have the highestpotential to protect patients treated with a variety of chemotherapydrugs while augmenting their efficacy in the treatment of many tumors.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

1. A method of increasing longevity in a subject, the method comprising:identifying if the subject's average daily protein intake level isgreater than a predetermined cutoff protein intake level; determiningamounts of plant-based and animal-based proteins consumed by thesubject; if the subject's average daily protein level is greater thanthe cutoff protein intake level, providing a low protein diet to thesubject if the subject is younger than a predetermined age, the lowprotein diet providing a percent calories from protein that is less thanthe predetermined cutoff protein intake level; and monitoring thesubject's IGF-1 levels to determine the frequency and type of diet. 2.The method of claim 1 wherein if the subject's age is older than thepredetermined age, a high protein diet is provided to the subject, thehigh protein diet having a protein calorie percentage that is greaterthan the predetermined cutoff protein intake level.
 3. The method ofclaim 1 wherein the low protein diet is provided to the subject for apredetermined number of days.
 4. The method of claim 3 wherein the lowprotein diet is provided to the subject for 3 to 7 days.
 5. The methodof claim 3 wherein the low protein is periodically provided to thesubject.
 6. The method of claim 5 wherein a frequency with which the lowprotein diet is provided to the subject is determined by the subject'slevels of insulin resistance, fasting glucose levels, IGF-I, IGFBP1,obesity, Body Mass Index, weight loss in previous 10 years, familyhistory of cancer, family history of diabetes, family history of earlymortality.
 7. The method of claim 3 wherein the low protein diet is afasting mimicking diet providing less than 10% of calories from proteinsand/or with all proteins being plant-based
 8. The method of claim 3wherein the low protein diet prevents or treats diabetes or cancer, anddelays age-related mortality and other age-related diseases.
 9. Themethod of claim 1 wherein the low protein diet provides 4.5 to 7kilocalories per pound of subject for a first day and 3 to 5kilocalories per pound of subject per day for a second to fifth day ofthe low protein diet, the low protein diet including: less than 30 g ofsugar on the first day; less than 20 g of sugar on the second to fifthdays; less than 28 g of proteins (all plant based) on the first day;less than 18 g of proteins (all plant based) on days the second to fifthdays; 20 to 30 grams of monounsaturated fats on the first day; 10 to15grams of monounsaturated fats on the second to fifth days; between 6 and10 grams of polyunsaturated fats on the first day; 3 to 5 grams ofpolyunsaturated fats on the second to fifth days; less than 12 g ofsaturated fats on the first day; less than 6 grams of saturated fats onthe second to fifth days; and 12 to 25 grams of glycerol per day on thesecond to fifth days.
 10. The method of claim 9 further comprisingadministering a second diet for a second time period to the subj ect,the second diet providing an overall calorie consumption that is within10 percent of the subject's normal calorie consumption for 25 to 26 daysfollowing the low protein diet.
 11. The method of claim 10 wherein thecombination of the low protein diet and the second diet provide thesubject with a total number of calories within 10 percent of thesubject's normal caloric intake.
 12. The method of claim 9 wherein thelow protein diet includes at least 50% of a daily recommended amount ofdietary fiber on all days.
 13. The method of claim 9 wherein level ofIGF-I decreases and a level of IGFBP1 increases.
 14. The method of claim3 wherein the low protein diet includes a supplement that providesexcess levels of non-essential amino acids to be consumed for a periodof 5 to 7 days every 2 weeks to 2 months together with very low proteinamounts or no protein diet.
 15. The method of claim 14 wherein greaterthan 70% of protein calories are plant based.
 16. The method of claim 14wherein the low protein diet is alternated with a normal protein diet,the low protein diet being provided for 7 days and a maximum of 2 monthswith 5-7 days of the supplement being provided every 2 weeks to 2 monthswith a normal diet of 1 to 7 weeks in between.
 17. The method of claim14 wherein the supplement provides one or more of the following aminoacids as a source of nitrogen: alanine, aspartic acid, cysteine,glutamic acid, glycine, histidine, proline, serine, and tyrosine whilesubstantially excluding isoleucine, leucine, lysine, methionine,phenyalanine, threonine, tryptophan, valine, and arginine such thatisoleucine, leucine, lysine, methionine, phenyalanine, threonine,tryptophan, valine, and arginine in combination are present in an amountthat is less than 5% of a total weight of the subject's diet.
 18. Themethod of claim 17 wherein isoleucine, leucine, lysine, methionine,phenyalanine, threonine, tryptophan, valine, and arginine in combinationare present in an amount that is less than 3% of a total weight of thesubject's diet.
 19. The method of claim 1 further comprising monitoringthe subjects IGFBP 1 level.
 20. The method of claim 1 wherein thepredetermined age is 65 years. 21.-43. (canceled)